INCOME TAXES (Schedule of components of temporary differences of deferred tax asset, net) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Accrued expenses	$ 16,000	$ 17,000
Allowance for doubtful accounts	1,000	1,000
Deferred revenue	8,000
Reserve for obsolescence	23,000	25,000
Expense associated with non-qualified stock options	37,000	37,000
Revenue Sharing Agreement	210,000	234,000
General business credit	1,004,000	1,198,000
NOL carryforward	5,732,000	7,241,000
Deferred tax assets, gross	7,031,000	18,753,000
Less: valuation allowance	(7,031,000)	(18,753,000)	$ (10,115,000)
Deferred tax asset, net