Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 3,117	$ 1,057
Investments	5,786	7,742
Trade receivables, less allowance for doubtful accounts of $11	965	896
Inventories	1,719	1,618
Other current assets	194	155
Total current assets	11,781	11,468
Deferred income tax asset, net	196	192
Intangible assets, net	555	565
Property and equipment, net	1,063	1,050
Total assets	13,595	13,275
Current liabilities
Current maturities of financing lease	5	5
Accounts payable	196	116
Accrued expenses	510	405
Accrued income tax	30	0
Total current liabilities	741	526
Long-term liabilities
Finance lease, net of current maturities	20	24
Total long-term liabilities	20	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	2,027	2,019
Retained earnings	10,426	10,335
Accumulated other comprehensive gain (unrealized gain on available-for-sale securities, net of income tax)	42	32
Total stockholders' equity	12,834	12,725
Total liabilities and stockholders' equity	$ 13,595	$ 13,275