Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statements Of Comprehensive Income [Abstract]
Net sales	$ 2,054	$ 1,837	$ 6,005	$ 5,562
Cost of goods sold	920	835	2,648	2,452
Gross profit	1,134	1,002	3,357	3,110
Operating expenses
Selling and marketing	342	387	1,127	1,262
General and administrative	402	386	1,225	1,199
Research and development	168	200	590	561
Total operating expenses	912	973	2,942	3,022
Operating income	222	29	415	88
Non-operating income (expense)
Interest expense	0	0	0	(1)
Interest income	9	3	22	18
Other income	3	3	8	12
Total non-operating income, net	12	6	30	29
Income before income taxes	234	35	445	117
Provision for income taxes	82	12	154	43
Net income	152	23	291	74
Other comprehensive income
Change in unrealized value of available-for-sale securities, net of income tax	6	2	10	6
Other comprehensive income	6	2	10	6
Net comprehensive income	$ 158	$ 25	$ 301	$ 80
Basic
Net income per share	$ 0.04	$ 0.01	$ 0.09	$ 0.02
Weighted average shares	3,395,521	3,395,521	3,395,521	3,395,521
Diluted
Net income per share	$ 0.04	$ 0.01	$ 0.09	$ 0.02
Weighted average shares	3,400,988	3,396,776	3,396,899	3,396,102