Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash Flows From Operating Activities:
Net income	$ 3,719,000	$ 5,342,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Stock-based compensation	101,000	91,000
Depreciation and amortization	198,000	182,000
Loss on marketable equity securities		59,000
Equity in income of unconsolidated affiliate	(322,000)	(87,000)
Operating lease expense, net of accretion	220,000	224,000
Changes in assets and liabilities:
Accounts receivable, net	1,384,000	(3,794,000)
Accounts receivable, related party	(370,000)	(192,000)
Inventories	(2,029,000)	155,000
Prepaid expenses	(4,011,000)	(650,000)
Accounts payable and accrued liabilities	(1,795,000)	1,072,000
Customer advance payments of orders	(96,000)	7,161,000
Lease liabilities	(219,000)	(221,000)
Net cash provided by (used in) operating activities	(3,220,000)	9,342,000
Cash Flows From Investing Activities:
Purchases of property and equipment	(130,000)	(288,000)
Proceeds from sales of marketable securities		47,000
Net cash used in investing activities	(130,000)	(241,000)
Cash Flows From Financing Activities:
Proceeds from exercise of stock options	308,000	1,841,000
Repurchase of common stock	(2,366,000)	(125,000)
Net cash provided by (used in) financing activities	(2,058,000)	1,716,000
Increase (decrease) in cash	(5,408,000)	10,817,000
Cash, beginning of the period	23,292,000	6,548,000
Cash, end of the period	$ 17,884,000	$ 17,365,000