Schedule of Valuation and Qualifying Accounts (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-09, Allowance, Credit Loss
Balance at beginning of year	$ 140,000	$ 140,000
Charges to statement of income	35,774	4,895
Write-offs	(5,774)	(4,895)
Balance at end of year	170,000	140,000
SEC Schedule, 12-09, Reserve, Inventory
Balance at beginning of year	457,000	579,000
Charges to statement of income	155,058	(15,477)
Write-offs	(12,058)	(106,523)
Balance at end of year	$ 600,000	$ 457,000