CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME
Net sales	$ 161,287	$ 166,562	$ 140,815
Cost of sales	112,068	117,763	98,066
Gross margin	49,219	48,799	42,749
Selling, general and administrative expense	23,784	23,363	22,223
Operating income	25,435	25,436	20,526
Interest income	4,168	1,877	1,197
Income before income taxes	29,603	27,313	21,723
Income tax expense	7,010	6,442	5,155
Net income	22,593	20,871	16,568
Other comprehensive loss, marketable securities adjustment:
Unrealized net income (loss) arising during year	11	(17)
Comprehensive income	$ 22,604	$ 20,854	$ 16,568
Net income per basic share	$ 1.84	$ 1.69	$ 1.34
Net income per diluted share	$ 1.84	$ 1.69	$ 1.34
Weighted average shares outstanding - basic	12,311	12,340	12,411
Weighted average shares outstanding - diluted	12,311	12,340	12,411