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Product Warranty Provisions (Tables)
12 Months Ended
Dec. 31, 2019
Product Warranty Provisions [Abstract]  
Schedule of accrued warranty activity
   December 31,
2018
   December 31,
2019
 
Balance at beginning of year  $2,279,831   $2,250,615 
Warranty costs incurred   (47,180)   (85,397)
Provision for the year   145,804    109,248 
Foreign exchange adjustment   (127,840)   (27,533)
Balance at end of year  $2,250,615   $2,246,933