Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 24,324	$ 21,536
Accounts receivable	65	93
Inventory	1,791	2,847
Prepaid expenses and other current assets	873	978
Total current assets	27,053	25,454
Property and equipment - net	329	325
Deferred tax assets	822	652
Other assets	168	161
Total assets	28,372	26,592
Current liabilities:
Accounts payable	1,095	760
Accrued liabilities	1,019	573
Liability related to early exercised stock options	132	152
Customer deposits	138	6
Total current liabilities	2,384	1,491
Other liabilities	139	133
Total liabilities	2,523	1,624
Commitments and contingencies (Note 5)
Stockholders’ equity
Additional paid-in-capital	17,988	17,580
Retained earnings	7,859	7,386
Total stockholders’ equity	25,849	24,968
Total liabilities and stockholders’ equity	28,372	26,592
Preferred Stock, Par Value
Stockholders’ equity
Preferred stock, par value $0.0001 per share - 5,000,000 shares authorized as of March 31, 2018 and December 31, 2017; nil shares issued and outstanding as of March 31, 2018 and December 31, 2017
Common Stock, Par Value
Stockholders’ equity
Common stock, par value $0.0001 per share - 75,000,000 shares authorized as of March 31, 2018 and December 31, 2017; 16,884,012 and 16,752,171 shares issued and outstanding as of March 31, 2018 and December 31, 2017, respectively	$ 2	$ 2