Organization And Summary Of Significant Accounting Policies (Schedule Of Product Warranty Liabilities) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Organization And Summary Of Significant Accounting Policies Schedule Of Product Warranty Liabilities
Balance at the beginning of the year	$ 247,850	$ 212,495
Amount accrued	46,322	180,797
Payments and credits	237,707	145,442
Balance at end of the year	$ 56,465	$ 247,850