CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statements of Comprehensive Income (Loss) [Abstract]
Net sales	$ 2,057	$ 2,216	$ 6,239	$ 6,915
Cost of goods sold	1,064	1,053	3,156	3,178
Gross profit	993	1,163	3,083	3,737
Operating expenses
Selling and marketing	307	357	1,021	1,230
General and administrative	494	497	1,458	2,125
Research and development	218	190	724	642
Total operating expenses	1,019	1,044	3,203	3,997
Operating income (loss)	(26)	119	(120)	(260)
Non-operating income
Interest expense	0	(1)	(1)	(1)
Interest income	109	36	297	44
Total non-operating income, net	109	35	296	43
Income (loss) before income tax expense (benefit)	83	154	176	(217)
Income tax expense (benefit)	75	32	96	(46)
Net income (loss)	8	122	80	(171)
Other comprehensive loss
Change in unrealized value of available-for-sale securities, net of income tax	(1)	(2)	(3)	0
Other comprehensive loss	(1)	(2)	(3)	0
Net comprehensive income (loss)	$ 7	$ 120	$ 77	$ (171)
Basic
Net income (loss) per share	$ 0	$ 0.04	$ 0.02	$ (0.05)
Weighted average shares	3,428,021	3,401,880	3,428,021	3,397,664
Diluted
Net income (loss) per share	$ 0	$ 0.04	$ 0.02	$ (0.05)
Weighted average shares	3,428,021	3,482,996	3,428,021	3,397,664