Condensed Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statements Of Comprehensive Income (Loss) [Abstract]
Net sales	$ 2,260	$ 1,780	$ 4,268	$ 3,496
Cost of goods sold	1,025	808	1,966	1,608
Gross profit	1,235	972	2,302	1,888
Operating expenses
Selling and marketing	516	401	1,001	836
General and administrative	418	424	890	956
Research and development	213	222	409	452
Total operating expenses	1,147	1,047	2,300	2,244
Operating income (loss)	88	(75)	2	(356)
Non-operating income (expense)
Interest expense	(1)	0	(1)	0
Interest income	41	24	85	47
Other income	3	3	5	5
Total non-operating income, net	43	27	89	52
Income (loss) before income tax expense (benefit)	131	(48)	91	(304)
Provision for (benefit of) income tax	28	(5)	19	(59)
Net income (loss)	103	(43)	72	(245)
Other comprehensive income
Change in unrealized value of available-for-sale securities, net of income tax	7	8	8	7
Other comprehensive income	7	8	8	7
Net comprehensive income (loss)	$ 110	$ (35)	$ 80	$ (238)
Basic
Net income (loss) per share	$ 0.03	$ (0.01)	$ 0.02	$ (0.07)
Weighted average shares	3,395,521	3,395,521	3,395,521	3,395,521
Diluted
Net income (loss) per share	$ 0.03	$ (0.01)	$ 0.02	$ (0.07)
Weighted average shares	3,395,521	3,395,521	3,395,521	3,395,521