Condensed Statements Of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statements Of Comprehensive Income (Loss) [Abstract]
Net sales	$ 1,923	$ 2,008
Cost of goods sold	924	941
Gross profit	999	1,067
Operating expenses
Selling and marketing	458	485
General and administrative	465	472
Research and development	217	196
Total operating expenses	1,140	1,153
Operating loss	(141)	(86)
Non-operating income (expense)
Loss on investment	(3)	0
Interest income	32	44
Other income	2	2
Total non-operating income, net	31	46
Loss before income tax benefit	(110)	(40)
Benefit from income tax	(19)	(9)
Net loss	(91)	(31)
Other comprehensive income
Change in unrealized value of available-for-sale securities, net of income tax	0	1
Other comprehensive income	0	1
Net comprehensive loss	$ (91)	$ (30)
Basic
Net loss per share	$ (0.03)	$ (0.01)
Weighted average shares	3,395,521	3,395,521
Diluted
Net loss per share	$ (0.03)	$ (0.01)
Weighted average shares	3,395,521	3,395,521