Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 25,185	$ 25,941
Accounts receivable	165	236
Inventory	2,759	2,207
Prepaid expenses and other current assets	926	936
Total current assets	29,035	29,320
Property and equipment - net	570	611
Deferred tax assets	686	560
Lease assets	681
Other assets	206	215
Total assets	31,178	30,706
Current liabilities:
Accounts payable	754	1,063
Accrued liabilities	890	718
Liability related to early exercised stock options	119	136
Customer deposits	154	2
Total current liabilities	2,534	1,919
Lease liabilities	617
Other liabilities	238	156
Total liabilities	2,772	2,075
Commitments and contingencies (Note 5)
Stockholders’ equity
Preferred stock, par value $0.0001 per share - 5,000,000 shares authorized as of March 31, 2019 and December 31, 2018; nil shares issued and outstanding as of March 31, 2019 and December 31, 2018
Common stock, par value $0.0001 per share - 75,000,000 shares authorized as of March 31, 2019 and December 31, 2018; 17,189,863 and 17,130,507 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	2	2
Additional paid-in-capital	19,751	19,358
Retained earnings	8,653	9,271
Total stockholders’ equity	28,406	28,631
Total liabilities and stockholders’ equity	$ 31,178	$ 30,706