Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows From Operating Activities
Net income (loss)	$ (618)	$ 473
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	247	51
Stock-based compensation	336	270
Deferred income taxes	(126)	(170)
Changes in operating assets and liabilities:
Accounts receivable	71	28
Inventory	(552)	1,056
Prepaid expenses and other current assets		105
Other assets	1	(8)
Accounts payable	(173)	356
Accrued expenses	195	446
Customer deposits	152	132
Lease liabilities	(38)
Other liabilities	(108)	6
Net cash provided by (used in) operating activities	(613)	2,745
Cash Flows From Investing Activities
Purchase of property and equipment	(183)	(75)
Net cash used in investing activities	(183)	(75)
Cash Flows From Financing Activities
Net proceeds from exercise of stock options	47	118
Payment for shares withheld for tax withholdings on vesting of restricted stock units	(7)
Net cash provided by financing activities	40	118
Net increase (decrease) in cash and cash equivalents	(756)	2,788
Cash and cash equivalents at beginning of period	25,941	21,536
Cash and cash equivalents at end of period	25,185	24,324
Supplemental Disclosure of Cash Flow Information
Cash paid for income taxes	13	20
Supplemental Disclosure of Noncash Investing and Financing Information
Vesting of early exercised options	17	$ 20
Property and equipment purchased but not yet paid	$ 16