Note 6 - Agreements and Commitments - Product Warranties (Details)	3 Months Ended
Mar. 31, 2019 USD ($)
Balance	$ 432,225
Current year warranty expense	313,894
Change in estimate related to pre-existing warranties
Payments made
Foreign currency effect	(11,588)
Balance	$ 734,531

Carrying value as of the balance sheet date of obligations incurred through that date and payable for estimated claims under standard and extended warranty protection rights granted to customers.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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-Subparagraph (SX 210.9-03.15(5))
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-Name Accounting Standards Codification
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Amount of decrease in the standard and extended product warranty accrual from payments made in cash or in kind to satisfy claims under the terms of the standard and extended product warranty.

+ References

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Amount of increase (decrease) in the standard and extended product warranty accrual from changes in estimates attributable to preexisting product warranties.

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Amount of increase in the standard and extended product warranty accrual from warranties issued.

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Amount of foreign currency translation gain (loss) which decreases (increases) the standard and extended product warranty accrual.

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