BIO-RAD LABORATORIES, INC.

Exhibit 4.3

BIO-RAD LABORATORIES, INC.

THIS GLOBAL NOTE IS HELD BY THE DEPOSITARY (AS DEFINED IN THE FIRST SUPPLEMENTAL INDENTURE GOVERNING THIS NOTE) OR ITS NOMINEE IN CUSTODY FOR THE BENEFIT OF THE BENEFICIAL OWNERS HEREOF, AND IS NOT TRANSFERABLE TO ANY PERSON UNDER ANY CIRCUMSTANCES EXCEPT THAT (I) THE TRUSTEE MAY MAKE SUCH NOTATIONS HEREON AS MAY BE REQUIRED PURSUANT TO SECTION 3.02 OF THE FIRST SUPPLEMENTAL INDENTURE, (II) THIS GLOBAL NOTE MAY BE EXCHANGED IN WHOLE BUT NOT IN PART PURSUANT TO SECTION 3.02(a) OF THE FIRST SUPPLEMENTAL INDENTURE, (III) THIS GLOBAL NOTE MAY BE DELIVERED TO THE TRUSTEE FOR CANCELLATION PURSUANT TO SECTION 2.12 OF THE BASE INDENTURE AND (IV) THIS GLOBAL NOTE MAY BE TRANSFERRED TO A SUCCESSOR DEPOSITARY WITH THE PRIOR WRITTEN CONSENT OF THE COMPANY.

UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR NOTES IN DEFINITIVE FORM, THIS NOTE MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR DEPOSITARY. UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (55 WATER STREET, NEW YORK, NEW YORK) (“DTC”) TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS MAY BE REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR SUCH OTHER ENTITY AS MAY BE REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

BIO-RAD LABORATORIES, INC.

4.875% Senior Notes due 2020

Bio-Rad Laboratories, Inc., a corporation duly organized and existing under the laws of the State of Delaware (herein called the “Company”, which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to CEDE & CO., or its registered assigns, the principal sum of Four Hundred Twenty-Five Million Dollars ($425,000,000) on December 15, 2020, and to pay interest thereon from December 9, 2010 or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually on June 15 and December 15 in each year, commencing June 15, 2011, to the Persons in whose names the Notes are registered at the close of business on the immediately preceding June 1 or December 1, as the case may be, at the rate of 4.875% per annum, until the principal hereof is paid or made available for payment, provided, however that any principal and premium, and any such installment of interest, which is overdue shall bear interest at the rate of 4.875% per annum (to the extent that the payment of such interest shall be legally enforceable), from the dates such amounts are due until they are paid or made available for payment, and such interest shall be payable on demand). The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Note (or one or more predecessor Notes) is registered at the close of business on the regular record date for such interest, which shall be the June 1 or December 1 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date. Interest on the Notes will be computed on the basis of a 360-day year of twelve 30-day months.

Payment of the principal of (and premium, if any) and any such interest on this Note will be made at the office or agency of the Company maintained for that purpose, in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts; provided, however, that at the option of the Company payment of interest may be made by check mailed to the address of the Person entitled thereto as such address shall appear in the Security Register.

Reference is hereby made to the further provisions of this Note set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place.

Unless the certificate of authentication hereon has been executed by the Trustee referred to on the reverse hereof by manual signature, this Note shall not be entitled to any benefit under the Indenture or be valid or obligatory for any purpose.

IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed.

CERTIFICATE OF AUTHENTICATION

This is one of the Notes of the series designated therein referred to in the within-mentioned Indenture.

Dated: December 9, 2010

[Reverse of Note]

This Note is one of a duly authorized issue of Securities of the Company (herein called the “Notes”), issued and to be issued in one or more series under an Indenture, dated as of December 9, 2010 (herein called the “Base Indenture”), between the Company and Wilmington Trust FSB, as trustee (herein called the ‘“Trustee”), as supplemented by the First Supplemental Indenture, dated as of December 9, 2010 (the “First Supplemental Indenture”), by and between the Company and the Trustee. The Base Indenture as supplemented by the First Supplemental Indenture is referred to herein as the “Indenture.” Capitalized terms used herein and not otherwise defined shall have the meanings given them in the Base Indenture or the First Supplemental Indenture, as applicable. The terms of the Notes include those stated in the Indenture and those made part of the Indenture by reference to the TIA as in effect on the date the Indenture is qualified. The Notes are subject to all such terms, and Holders are referred to the Indenture and TIA for a statement of such terms.

The Notes of this series are subject to redemption at any time, upon not less than 30 days’ and not more than 60 days’ notice by mail, as a whole or from time to time in part, at the election of the Company, on any date prior to their Stated Maturity at a Redemption Price equal to the greater of (i) 100% of the principal amount of such Notes to be redeemed, and (ii) the sum of the present values of the Remaining Scheduled Payments (as defined below) of the Notes to be redeemed, discounted to the Redemption Date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined below) plus 35 basis points, plus, accrued and unpaid interest thereon to the Redemption Date. Notwithstanding the foregoing, installments of interest on the Notes that are due and payable on Interest Payment Dates falling on or prior to a Redemption Date will be payable on the Interest Payment Date to the registered Holders as of the close of business on the relevant record date according to the Notes and the Indenture.

“Comparable Treasury Issue” means the United States Treasury security selected by an Independent Investment Banker as having an actual or interpolated maturity comparable to the remaining term of the Notes to be redeemed that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of such Notes to be redeemed.

“Comparable Treasury Price” means, with respect to any Redemption Date, (a) the arithmetic average of the Reference Treasury Dealer Quotations for such redemption date, after excluding the highest and lowest of the Reference Treasury Dealer Quotations, (b) if fewer than four Reference Treasury Dealer Quotations are obtained, the arithmetic average of all of those quotations or (c) if only one Reference Treasury Dealer Quotation is obtained, such Reference Treasury Dealer Quotation.

“Independent Investment Banker” means one of the Reference Treasury Dealers appointed by the Company.

“Reference Treasury Dealer” means each of Credit Suisse Securities (USA) LLC and Goldman, Sachs & Co., and their respective successors, or if at any time any of the above is not a primary U.S. Government securities dealer, any other nationally recognized investment

banking firm selected by the Company that is a primary U.S. Government securities dealer, as well as two other nationally recognized investment banking firms selected by the Company that are primary U.S. Government securities dealers.

“Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any Redemption Date, the arithmetic average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Trustee by such Reference Treasury Dealer at 5:00 p.m., New York City time, on the third Business Day preceding such Redemption Date.

“Remaining Scheduled Payments” means, with respect to any Note to be redeemed, the remaining scheduled payments of the principal thereof and interest thereon that would be due after the related Redemption Date for such redemption; provided, however, that, if such Redemption Date is not an Interest Payment Date with respect to such Note, the amount of the next succeeding scheduled interest payment thereon will be reduced by the amount of interest accrued thereon to such Redemption Date.

“Treasury Rate” means, for any Redemption Date, the rate per annum equal to the semi-annual equivalent yield to Maturity, computed as of the second Business Day immediately preceding that Redemption Date, of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such Redemption Date.

In the event of redemption of this Note in part only, a new Note or Notes of this series and of like tenor for the unredeemed portion hereof will be issued in the name of the Holder hereof upon the cancellation hereof.

The Indenture contains provisions for defeasance at any time of the entire indebtedness of this Note or certain restrictive covenants and Events of Default with respect to this Note, in each case upon compliance with certain conditions set forth in the Indenture.

If an Event of Default with respect to Notes of this series shall occur and be continuing, the principal of the Notes of this series may be declared due and payable in the manner and with the effect provided in the Indenture.

The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the rights of the Holders of the Notes to be affected under the Indenture at any time by the Company and the Trustee with the consent of the Holders of a majority in principal amount of the Notes at the time outstanding to be affected. The Indenture also contains provisions permitting the Holders of specified percentages in principal amount of the Notes at the time outstanding, on behalf of the Holders of all Notes, to waive compliance by the Company with certain provisions of the Indenture and certain past defaults under the Indenture and their consequences. Any such consent or waiver by the Holder of this Note shall be conclusive and binding upon such Holder and upon all future Holders of this Note and of any Note issued upon the registration of transfer hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Note.

As provided in and subject to the provisions of the Indenture, the Holder of this Note shall not have the right to institute any proceeding with respect to the Indenture or for the appointment of a receiver or trustee or for any other remedy thereunder, unless such Holder shall have previously given the Trustee written notice of a continuing Event of Default with respect to the Notes, the Holders of not less than 25% in principal amount of the Notes at the time outstanding shall have made written request to the Trustee to institute proceedings in respect of such Event of Default as Trustee and offered the Trustee indemnity or security satisfactory to it, and the Trustee shall not have received from the Holders of a majority in principal amount of Notes of this series at the time outstanding a direction inconsistent with such request, and shall have failed to institute any such proceeding, for 60 days after receipt of such notice, request and offer of indemnity. The foregoing shall not apply to any suit instituted by the Holder of this Note for the enforcement of any payment of principal hereof or any premium or interest hereon on or after the respective due dates expressed herein.

No reference herein to the Indenture and no provision of this Note or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional, to pay the principal of and any premium and interest on this Note at the times, place and rate, and in the coin or currency, herein prescribed.

As provided in the Indenture and subject to certain limitations therein set forth, the transfer of this Note may be registered and this Note may be exchanged as provided in the Indenture.

The Notes of this series are issuable only in registered form without coupons in denominations of $2,000 and integral multiples of $1,000 in excess thereof.

No service charge shall be made for any such registration of transfer or exchange, but the Company may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith.

Prior to due presentment of this Note for registration of transfer, the Company, the Trustee and any agent of the Company or the Trustee may treat the Person in whose name this Note is registered as the owner hereof for all purposes, whether or not this Note be overdue, and neither the Company, the Trustee nor any such agent shall be affected by notice to the contrary.

The Notes of this series shall be governed by and construed in accordance with the laws of the State of New York (including without limitation Section 5-1401 of the New York General Obligations Law or any successor to such statute). The Trustee and the Company agree to submit to the non-exclusive jurisdiction of any United States federal or state court located in the borough of Manhattan, in the city of New York in any action or proceeding arising out of or relating to the Notes.

All terms used in this Note which are defined in the Indenture shall have the meanings assigned to them in the Indenture.

ASSIGNMENT FORM

To assign this Note, fill in the form below:

I or we assign and transfer this Note to:

(Insert assignee’s social security or tax I.D. no.)

(Print or type assignee’s name, address and zip code)

and irrevocably appoint                                          as agent to transfer this Note on the books of the Company. The agent may substitute another to act for him.

SCHEDULE OF EXCHANGES OF INTERESTS IN THE GLOBAL NOTE

The following exchanges of an interest in this Global Note for an interest in another Global Note or for a Definitive Note, or exchanges of an interest in another Global Note or a Definitive Note for an interest in this Global Note have been made: