Offer Letter, dated May 11, 2014, between the Registrant and Thomas Chuang

Position. Your initial title will be Director of Finance, and you will initially report to the CEO. This is a full-time position. While you render services to the Company, you will not engage in any other employment, consulting or other business activity (whether full-time or part-time) that would create a conflict of interest with the Company. By signing this letter agreement, you confirm to the Company that you have no contractual commitments or other legal obligations that would prohibit you from performing your duties for the Company.

Cash Compensation. The Company will pay you a starting salary at the rate of $115,000 per year, payable in accordance with the Company’s standard payroll schedule. This salary will be subject to adjustment pursuant to the Company’s employee compensation policies in effect from time to time.

Employee Benefits. As a regular employee of the Company, you will be eligible to participate in a number of Company-sponsored benefits. In addition, you will be entitled to paid time off in accordance with the Company’s paid time off policy, as in effect from time to time. A copy of the current paid time off policy is attached hereto as Exhibit B. In addition, you will be eligible to participate in the Company’s group health insurance plan, a description of which is attached hereto as Exhibit C. No guarantee is made as to the continuation of this group health insurance plan or any other.

Stock Options. Subject to the approval of the Company’s Board of Directors or its Compensation Committee, you will be granted an option to purchase 32,500 shares of the Company’s Common Stock (the “Option”). The exercise price per share of the Option will be determined by the Board of Directors or the Compensation Committee when the Option is granted. The Option will be subject to the terms and conditions applicable to options granted under the Company’s 2010 Stock Plan (the “Plan”), as described in the Plan and the applicable Stock Option Agreement. You will vest in 20% of the Option shares after 12 months of continuous service, and the balance will vest in equal monthly installments over the next 48 months of continuous service, as described in the applicable Stock Option Agreement.

Proprietary Information and Inventions Agreement. Like all Company employees, you will be required, as a condition of your employment with the Company, to sign the Company’s standard Proprietary Information and Inventions Agreement, a copy of which is attached hereto as Exhibit A.

Employment Relationship. Employment with the Company is for no specific period of time. Your employment with the Company will be “at will,” meaning that either you or the Company may terminate your employment at any time and for any reason, with or without cause. Any contrary representations that may have been made to you are superseded by this letter agreement. This is the full and complete agreement between you and the Company on this term. Although your job duties, title, compensation and benefits, as well as the Company’s personnel policies and procedures, may change from time to time, the “at will” nature of your employment may only be changed in an express written agreement signed by you and a duly authorized officer of the Company (other than you).

Tax Matters.

Withholding. All forms of compensation referred to in this letter agreement are subject to reduction to reflect applicable withholding and payroll taxes and other deductions required by law.

Tax Advice. You are encouraged to obtain your own tax advice regarding your compensation from the Company. You agree that the Company does not have a duty to design its compensation policies in a manner that minimizes your tax liabilities, and you will not make any claim against the Company or its Board of Directors related to tax liabilities arising from your compensation.

Interpretation, Amendment and Enforcement. This letter agreement and Exhibit A constitute the complete agreement between you and the Company, contain all of the terms of your employment with the Company and supersede any prior agreements, representations or understandings (whether written, oral or implied) between you and the Company. This letter agreement may not be amended or modified, except by an express written agreement signed by both you and a duly authorized officer of the Company. The terms of this letter agreement and the resolution of any disputes as to the meaning, effect, performance or validity of this letter agreement or arising out of, related to, or in any way connected with, this letter agreement, your employment with the Company or any other relationship between you and the Company (the “Disputes”) will be governed by California law, excluding laws relating to conflicts or choice of law. You and the Company submit to the exclusive personal jurisdiction of the federal and state courts located in San Francisco County in connection with any Dispute or any claim related to any Dispute.

/s/ Thomas Chuang

Signature of Employee

Dated:

May 12, 2014