Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 1,025	$ 1,057
Investments	7,752	7,742
Trade receivables, less allowance for doubtful accounts of $11	1,295	896
Inventories	1,712	1,618
Other current assets	155	155
Total current assets	11,939	11,468
Deferred income tax asset, net	203	192
Intangible assets, net	457	565
Property and equipment, net	1,065	1,050
Total assets	13,664	13,275
Current liabilities
Current maturities of financing lease	5	5
Accounts payable	241	116
Accrued expenses	555	405
Accrued income tax	32	0
Total current liabilities	833	526
Long-term liabilities
Finance lease, net of current maturities	21	24
Total long-term liabilities	21	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	2,024	2,019
Retained earnings	10,407	10,335
Accumulated other comprehensive gain (unrealized gain on available-for-sale securities, net of income tax)	40	32
Total stockholders' equity	12,810	12,725
Total liabilities and stockholders' equity	$ 13,664	$ 13,275