The components of deferred income tax assets and liabilities are as follows (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets:
Allowance for doubtful accounts	$ 56,884	$ 50,100
Credit carryforwards	1,758,809	1,435,543
Inventory reserve	1,046,890	637,396
Loss contracts reserve	260,780	285,367
Restricted stock	189,072	87,976
Other	18,654	15,238
Acquisition costs	93,063	100,774
Lease liability	950,141	934,463
Disallowed interest expense	909,800	749,228
Net operating loss carryforward	20,953,330	21,016,334
Deferred tax assets	26,237,423	25,312,419
Valuation allowance	(22,704,931)	(21,632,564)
Deferred Tax Liabilities:
Prepaid expenses	115,437	114,738
Revenue recognition	2,086,045	2,133,348
Property and equipment	441,590	588,252
ROU asset	889,420	843,517
Deferred tax liabilities	3,532,492	3,679,855
Net deferred tax assets (liabilities)