Note 8 - Concentration of Credit Risk - Concentration of Credit Risk, Net Sales (Details) - USD ($)	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Net Sales	$ 5,797,000	$ 6,599,000
Customer One [Member]
Net Sales	$ 2,502,000	$ 3,991,000
Customer One [Member] \| Customer Concentration Risk [Member] \| Revenue Benchmark [Member]
Percent of net sales	43.00%	60.00%
Customer Two [Member]
Net Sales	$ 1,347,000	$ 1,294,000
Customer Two [Member] \| Customer Concentration Risk [Member] \| Revenue Benchmark [Member]
Percent of net sales	23.00%	19.00%

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9038-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130545-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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+ Details