Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 8,785	$ 1,057
Treasury bills	0	7,697
Available-for-sale securities	45	45
Trade receivables, less allowance for doubtful accounts of $11	1,036	896
Inventories	1,695	1,618
Other current assets	159	155
Total current assets	11,720	11,468
Deferred income tax asset	203	192
Intangible assets, net	489	565
Property and equipment, net	1,063	1,050
Total assets	13,475	13,275
Current liabilities
Current maturity of financing lease	5	5
Accounts payable	129	116
Accrued expenses	431	405
Total current liabilities	565	526
Long-term liabilities
Financing lease, net of current maturities	19	24
Total long-term liabilities	19	24
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	2,030	2,019
Retained earnings	10,522	10,335
Accumulated other comprehensive gain (unrealized gain on available-for-sale securities, net of income tax)	0	32
Total stockholders' equity	12,891	12,725
Total liabilities and stockholders' equity	$ 13,475	$ 13,275