Annual report pursuant to Section 13 and 15(d)

Product warranty (Tables)

v3.20.4
Product warranty (Tables)
12 Months Ended
Dec. 31, 2020
Guarantees [Abstract]  
Schedule of Product Warranty Reserve
Changes in our warranty reserve were as follows:
Warranty reserve, December 31, 2018 $ 140,600 
Warranty provision for units sold 535,700 
Costs of warranty incurred (471,000)
Warranty reserve, December 31, 2019 205,300 
Warranty provision for units sold 185,696 
Costs of warranty incurred (226,196)
Warranty reserve, December 31, 2020 $ 164,800