Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue
Total revenue	$ 9,825	$ 10,189
Cost of goods sold	8,225	7,967
Gross profit	1,600	2,222
General and administrative expenses	1,051	1,208
Selling expenses	591	567
Total operating expenses	1,642	1,775
Operating income	(42)	447
Other income (expense)
Interest expense	(56)	(44)
Interest income	9	11
Gain (loss) on sale of assets	36	2
Other income (expense)	4	14
Total other income (expense)	(7)	(17)
Income (loss) before income tax expense (benefit)	(49)	430
Income tax expense	(11)	99
Net income	$ (38)	$ 331
Basic earnings (loss) per share	$ (0.01)	$ 0.06
Weighted average number of common shares outstanding:
Basic (in thousands)	5,183	5,134
Diluted (in thousands)	5,183	5,142
Product sales
Revenue
Total revenue	$ 6,852	$ 7,503
Barrier rentals
Revenue
Total revenue	742	573
Royalty income
Revenue
Total revenue	268	306
Shipping and installation revenue
Revenue
Total revenue	$ 1,963	$ 1,807