Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash Flows From Operating Activities
Net income	$ 456	$ 1,174
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	256	253
Stock-based compensation	1,136	1,021
Accretion of investment premium, net of amortization of discount	83
Inventory valuation adjustment	133	266
Deferred income taxes	106	(15)
Noncash lease expense	512	475
Changes in operating assets and liabilities:
Accounts receivable	30	156
Inventory	(1,803)	(4,910)
Prepaid expenses and other current assets	267	52
Other assets	(6)	2
Accounts payable	(615)	590
Accrued expenses	(498)	320
Customer deposits	(431)	3,396
Lease liabilities	(117)	(280)
Other liabilities	(359)	(240)
Net cash provided by (used in) operating activities	(850)	2,260
Cash Flows From Investing Activities
Purchase of property and equipment	(346)	(267)
Purchase of debt securities	(11,065)
Proceeds from maturities of debt securities	5,750
Net cash used in investing activities	(5,661)	(267)
Cash Flows From Financing Activities
Net proceeds from exercise of stock options	120	128
Payment for shares withheld for tax withholdings on vesting of restricted stock units	(74)	(57)
Net cash provided by financing activities	46	71
Net increase (decrease) in cash and cash equivalents	(6,465)	2,064
Cash and cash equivalents at beginning of period	11,391	25,941
Cash and cash equivalents at end of period	4,926	28,005
Supplemental Disclosure of Cash Flow Information
Cash paid for income taxes	66	35
Supplemental Disclosure of Noncash Investing and Financing Information
Property and equipment purchased but not yet paid	134	33
Vesting of early exercised options	$ 36	$ 51