CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 9,348,000	$ 4,276,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,895,000	1,899,000
Non-cash operating lease expense	435,000	384,000
Provision for doubtful accounts	244,000	43,000
Deferred taxes	865,000	289,000
Foreign currency transaction gains	(45,000)	(181,000)
Share-based compensation	999,000	863,000
Unrealized (gain) loss on available-for-sale equity security	(14,000)	23,000
Changes in operating assets and liabilities:
Accounts and trade notes receivable	(12,208,000)	(1,721,000)
Inventories	(1,142,000)	(6,380,000)
Prepaid expenses and other assets	(663,000)	(785,000)
Accounts payable	5,594,000	3,060,000
Advance customer payments and other	(45,000)	208,000
Accrued expenses	487,000	1,120,000
Operating leases	(632,000)	(616,000)
Net cash provided by operating activities	5,118,000	2,482,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of available-for-sale marketable securities	8,682,000	9,016,000
Proceeds from sales of available-for-sale marketable securities	225,000	0
Purchases of available-for-sale marketable securities	(9,462,000)	(10,637,000)
Additions to equipment and leasehold improvements	(1,570,000)	(1,049,000)
Additions to patents	(208,000)	(115,000)
Net cash used in investing activities	(2,333,000)	(2,785,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	292,000	322,000
Tax payments for shares withheld related to stock option exercises	(727,000)	(420,000)
Proceeds from issuance of common stock under employee stock purchase plan	247,000	224,000
Net cash provided by (used in) financing activities	(188,000)	126,000
Effects of exchange rate changes on cash and cash equivalents	9,000	6,000
Net increase (decrease) in cash and cash equivalents	2,606,000	(171,000)
Cash and cash equivalents – beginning of period	8,399,000	5,836,000
Cash and cash equivalents – end of period	$ 11,005,000	$ 5,665,000