Condensed Statements Of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statements Of Comprehensive Income (Loss) [Abstract]
Net sales	$ 1,901	$ 1,923
Cost of goods sold	911	924
Gross profit	990	999
Operating expenses
Selling and marketing	348	458
General and administrative	443	465
Research and development	203	217
Total operating expenses	994	1,140
Operating loss	(4)	(141)
Non-operating income (expense)
Loss on investment	0	(3)
Interest income	2	32
Other income	0	2
Total non-operating income, net	2	31
Loss before income tax benefit	(2)	(110)
Benefit of income tax	0	(19)
Net loss	(2)	(91)
Other comprehensive income
Change in unrealized value of available-for-sale securities, net of income tax	0	0
Other comprehensive income	0	0
Net comprehensive loss	$ (2)	$ (91)
Basic
Net loss per share	$ 0.00	$ (0.03)
Weighted average shares	3,395,521	3,395,521
Diluted
Net loss per share	$ 0.00	$ (0.03)
Weighted average shares	3,395,521	3,395,521