Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 7,604	$ 6,713
Investments	2,056	3,056
Trade receivables, less allowance for doubtful accounts of $11	1,155	1,005
Inventories	1,758	1,663
Other current assets	209	188
Income tax receivable	2	3
Total current assets	12,784	12,628
Deferred income tax asset, net	214	208
Intangible assets, net	25	38
Property and equipment, net	993	1,017
Total assets	14,016	13,891
Current liabilities
Current maturities of financing lease	6	6
Accounts payable	326	349
Accrued expenses	499	342
Total current liabilities	831	697
Long-term liabilities
Financing lease, net of current maturities	5	6
Total long-term liabilities	5	6
Commitments and contingencies
Stockholders' equity
Common stock par value $0.10 per share; authorized 10,000,000 shares; 3,395,521 shares issued and outstanding	339	339
Additional paid-in capital	2,042	2,041
Retained earnings	10,799	10,808
Total stockholders' equity	13,180	13,188
Total liabilities and stockholders' equity	$ 14,016	$ 13,891