Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statements Of Comprehensive Income [Abstract]
Net sales	$ 2,301	$ 2,009	$ 3,951	$ 3,725
Cost of goods sold	977	835	1,728	1,617
Gross profit	1,324	1,174	2,223	2,108
Operating expenses
Selling and marketing	408	448	785	875
General and administrative	379	331	823	813
Research and development	201	188	422	361
Total operating expenses	988	967	2,030	2,049
Operating income	336	207	193	59
Non-operating income (expense)
Interest expense	0	0	0	(1)
Interest income	5	4	13	15
Other income	2	6	5	9
Total non-operating income, net	7	10	18	23
Income before income taxes	343	217	211	82
Provision for income taxes	120	77	72	31
Net income	223	140	139	51
Other comprehensive income
Change in unrealized value of available-for-sale securities, net of income tax	4	4	4	4
Other comprehensive income	4	4	4	4
Net comprehensive income	$ 227	$ 144	$ 143	$ 55
Basic
Net income per share	$ 0.06	$ 0.04	$ 0.04	$ 0.01
Weighted average shares	3,395,521	3,395,521	3,395,521	3,395,521
Diluted
Net income per share	$ 0.06	$ 0.04	$ 0.04	$ 0.01
Weighted average shares	3,402,527	3,395,521	3,402,731	3,395,521