Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue
Total revenue	$ 15,218	$ 9,825
Cost of goods sold	9,496	8,225
Gross profit	5,722	1,600
Operating expenses
General and administrative expenses	1,325	1,051
Selling expenses	595	591
Total operating expenses	1,920	1,642
Operating income (loss)	3,802	(42)
Other income (expense)
Interest expense	(42)	(56)
Interest income	9	9
Gain (loss) on sale of assets	46	36
Other income (expense)	(7)	4
Total other income (expense)	6	(7)
Income (loss) before income tax expense (benefit)	3,808	(49)
Income tax expense (benefit)	941	(11)
Net income (loss)	$ 2,867	$ (38)
Basic and diluted earnings (loss) per common share	$ 0.55	$ (0.01)
Weighted average number of common shares outstanding:
Basic (in thousands)	5,202	5,183
Diluted (in thousands)	5,210	5,183
Product Sales
Revenue
Total revenue	$ 7,420	$ 6,852
Barrier Rentals
Revenue
Total revenue	5,777	742
Royalty Income
Revenue
Total revenue	420	268
Shipping and Installation Revenue
Revenue
Total revenue	$ 1,601	$ 1,963