Consolidated Statements of Income - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Revenue
Products sales and leasing	$ 33,322,000	$ 30,983,000
Shipping and installation revenue	6,510,000	7,273,000
Royalties	1,885,000	1,794,000
Total revenue	41,717,000	40,050,000
Cost of goods sold	30,136,000	29,701,000
Gross profit	11,581,000	10,349,000
General and administrative expenses	5,370,000	3,891,000
Selling expenses	2,496,000	2,122,000
Total operating expenses	7,866,000	6,013,000
Operating income	3,715,000	4,336,000
Other income (expense)
Interest expense	(184,000)	(162,000)
Interest income	37,000	37,000
Gain on sale of assets	51,000	32,000
Other income	122,000	54,000
Total other income (expense)	26,000	(39,000)
Income before income tax expense	3,741,000	4,297,000
Income tax expense	1,057,000	1,462,000
Net income	$ 2,684,000	$ 2,835,000
Basic earnings per share (in dollars per share)	$ 0.53	$ 0.57
Diluted earnings per share (in dollars per share)	$ 0.53	$ 0.56