Note 10 - Concentration of Credit Risk - Concentration of Credit Risk, Net Sales (Details) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net Sales	$ 6,325,241	$ 5,745,353	$ 13,741,409	$ 12,812,854
Customer One [Member]
Net Sales	$ 3,421,000	$ 2,508,000	$ 7,344,000	$ 5,675,000
Customer One [Member] \| Customer Concentration Risk [Member] \| Revenue Benchmark [Member]
Percent of net sales	54.00%	43.00%	53.00%	44.00%
Customer Two [Member]
Net Sales	$ 812,000	$ 947,000	$ 2,106,000	$ 2,110,000
Customer Two [Member] \| Customer Concentration Risk [Member] \| Revenue Benchmark [Member]
Percent of net sales	13.00%	16.00%	15.00%	17.00%

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details