Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue
Total revenue	$ 40,220	$ 41,717
Cost of goods sold	29,730	30,253
Gross profit	10,490	11,464
General and administrative expenses	5,675	5,253
Selling expenses	2,599	2,496
Total operating expenses	8,274	7,749
Operating income	2,216	3,715
Other income (expense)
Interest expense	(176)	(184)
Interest income	42	37
Gain on sale of assets	126	51
Other income	51	122
Total other income (expense)	43	26
Income before income tax expense	2,259	3,741
Income tax expense	572	1,057
Net income	$ 1,687	$ 2,684
Basic earnings per share	$ 0.33	$ 0.53
Diluted earnings per share	$ 0.33	$ 0.53
Product sales
Revenue
Total revenue	$ 29,159	$ 29,055
Barrier rentals
Revenue
Total revenue	1,729	4,267
Royalties
Revenue
Total revenue	1,675	1,885
Shipping and installation
Revenue
Total revenue	$ 7,657	$ 6,510