3. REVENUE FROM CONTRACTS WITH CUSTOMERS (Details - Contract balances) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Billings In Excess Of Costs And Estimated Earnings On Uncompleted Contracts And Deferred Revenues
Costs incurred on uncompleted contracts	$ 2,072	$ 2,098
Estimated earnings on uncompleted contracts	3,155	3,153
Gross costs and estimated earnings	5,227	5,251
Less: Billings to date on uncompleted contracts	(5,703)	(5,792)
Costs incurred plus estimated earning less billings on uncompleted contracts, net	(476)	(541)
Included in the accompanying condensed consolidated balance sheets under the following captions:
Contract Assets	214	189
Contract Liabilities	(690)	(730)
Costs incurred plus estimated earning less billings on uncompleted contracts	$ (476)	$ (541)