CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statements of Comprehensive Income (Loss) [Abstract]
Net sales	$ 2,217	$ 2,137	$ 4,461	$ 4,182
Cost of goods sold	1,170	1,069	2,334	2,092
Gross profit	1,047	1,068	2,127	2,090
Operating expenses
Selling and marketing	353	344	704	714
General and administrative	537	442	1,104	964
Research and development	264	238	526	506
Total operating expenses	1,154	1,024	2,334	2,184
Operating income (loss)	(107)	44	(207)	(94)
Non-operating income
Interest expense	0	(1)	0	(1)
Interest income	109	95	225	188
Total non-operating income, net	109	94	225	187
Income before income tax expense	2	138	18	93
Income tax expense	6	22	11	21
Net income (loss)	(4)	116	7	72
Other comprehensive income (loss)
Change in unrealized value of available-for-sale securities, net of income tax	0	2	0	(2)
Other comprehensive income (loss)	0	2	0	(2)
Net comprehensive income (loss)	$ (4)	$ 118	$ 7	$ 70
Basic
Net income (loss) per share	$ 0	$ 0.03	$ 0	$ 0.02
Weighted average shares	3,428,021	3,428,021	3,428,021	3,428,021
Diluted
Net income (loss) per share	$ 0	$ 0.03	$ 0	$ 0.02
Weighted average shares	3,428,021	3,443,394	3,428,021	3,443,930