Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 5,540	$ 7,646
Investments	4,023	2,036
Trade receivables, less allowance for credit losses of $11	1,372	1,161
Inventories	1,779	1,745
Other current assets	215	214
Income tax receivable	0	11
Total current assets	12,929	12,813
Deferred income tax asset, net	306	256
Property and equipment, net	952	975
Total assets	14,187	14,044
Current liabilities
Current maturities of financing lease	4	6
Accounts payable	357	274
Accrued expenses	423	350
Accrued income taxes	37	0
Total current liabilities	821	630
Commitments and contingencies
Stockholders' equity
Common stock par value $0.10 per share; authorized 10,000,000 shares; 3,428,021 shares issued and outstanding, respectively	342	342
Additional paid-in capital	2,163	2,163
Retained earnings	10,864	10,908
Accumulated other comprehensive income (loss) (unrealized income (loss) on available-for-sale securities, net of income tax)	(3)	1
Total stockholders' equity	13,366	13,414
Total liabilities and stockholders' equity	$ 14,187	$ 14,044