Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income	$ 1,306	$ 146
Adjustments to reconcile net income (loss) to operating cash flow:
Depreciation and amortization	815	806
Non-cash interest expense	6	6
Non-cash rent expense	0	(11)
Bad debt expense	0	1
Deferred revenue	(8)	(24)
Stock-based compensation	153	117
Deferred income taxes	0	370
Loss (gain) on sale of property and equipment	7	(5)
(Increase) decrease in operating assets:
Accounts receivable	(1,959)	(1,739)
Inventories	193	(491)
Refundable income taxes	(15)	(346)
Prepaid expenses and other current assets	54	312
Increase (decrease) in operating liabilities:
Accounts payable	(301)	833
Accrued expenses	398	(981)
Operating lease asset amortization/liability	0	(11)
Accrued income taxes	561	(38)
Net cash provided by (used in) operating activities	1,210	(1,055)
Cash flows from investing activities:
Purchases of property and equipment	(518)	(403)
Proceeds from sale of property and equipment	0	5
Net cash used in investing activities	(518)	(398)
Cash flows from financing activities:
Purchase of treasury stock	0	(405)
Net cash used in financing activities	0	(405)
Net increase (decrease) in cash and cash equivalents	692	(1,858)
Cash and cash equivalents at the beginning of the period	7,926	3,836
Cash and cash equivalents at the end of the period	8,618	1,978
Supplemental cash flow information:
Cash paid for income taxes, net of (refunds)	47	65
Cash paid for interest	16	35
Non-cash investing and financing activities
Increase (decrease) in right-of-use assets and operating lease obligations	21	113
Issuance of common stock under equity incentive plans	$ 0	$ 516