Note 4 - Reclassifications (Details Textual) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Cost of Goods and Services Sold, Total	$ 1,467,323		$ 1,536,842	$ 2,755,668	$ 2,904,525
Revenue from Contract with Customer, Including Assessed Tax	$ 3,279,399		3,885,887	6,459,716	7,322,151
Reclassified Certain Sales Rebates From Cost of Sales to Net Sales [Member]
Cost of Goods and Services Sold, Total		$ (101,706)	(73,330)	(101,706)	(156,579)
Revenue from Contract with Customer, Including Assessed Tax		$ (101,706)	$ (73,330)	$ (101,706)	$ (156,579)

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 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

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