CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 4,550,000	$ 2,477,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,292,000	1,304,000
Non-cash operating lease expense	287,000	272,000
Provision (recovery) for doubtful accounts	174,000	(9,000)
Deferred taxes	388,000	(48,000)
Foreign currency transaction losses (gains)	16,000	(305,000)
Share-based compensation	671,000	558,000
Unrealized (gain) loss on available-for-sale equity security	(12,000)	18,000
Changes in operating assets and liabilities:
Accounts and trade notes receivable	(7,303,000)	1,357,000
Inventories	(3,493,000)	(5,006,000)
Prepaid expenses and other assets	(117,000)	(782,000)
Accounts payable	6,024,000	2,666,000
Advance customer payments and other	133,000	319,000
Accrued expenses	456,000	780,000
Operating leases	(409,000)	(395,000)
Net cash provided by operating activities	2,657,000	3,206,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of available-for-sale marketable securities	6,083,000	6,216,000
Proceeds from sales of available-for-sale marketable securities	225,000	0
Purchases of available-for-sale marketable securities	(6,775,000)	(7,980,000)
Additions to equipment and leasehold improvements	(936,000)	(477,000)
Additions to patents	(159,000)	(41,000)
Net cash used in investing activities	(1,562,000)	(2,282,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	67,000	256,000
Tax payments for shares withheld related to stock option exercises	0	(420,000)
Net cash provided by (used in) financing activities	67,000	(164,000)
Effects of exchange rate changes on cash and cash equivalents	6,000	13,000
Net increase in cash and cash equivalents	1,168,000	773,000
Cash and cash equivalents – beginning of period	8,399,000	5,836,000
Cash and cash equivalents – end of period	$ 9,567,000	$ 6,609,000