CONDENSED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 32,341	$ 40,599
Accounts receivable, net of allowance of $28 and $19, respectively	2,797	2,012
Notes receivable, net of allowance of $8 and $9, respectively	369	444
Inventories	10,152	13,473
Prepaid and other current assets	1,000	1,857
Total current assets	46,659	58,385
Property and equipment, net	1,015	832
Equipment under lease, net	5,709	3,583
Notes and other receivables, long-term, net of allowance of $4 and $9, respectively	190	452
Intangible assets, net	11,179	12,110
Other assets	3,349	3,758
Total assets	68,101	79,120
Current liabilities:
Accounts payable	2,399	2,481
Accrued liabilities	4,204	4,570
Deferred revenue	922	923
Other current liabilities	507	493
Total current liabilities	8,032	8,467
Long-term operating lease liabilities	2,933	3,314
Other long-term liabilities	90	129
Total liabilities	11,055	11,910
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, par value $0.01 per share, 10,000 shares authorized at September 30, 2021 and December 31, 2020; no shares issued and outstanding at September 30, 2021 and December 31, 2020
Common stock, par value $0.01 per share, 150,000 shares authorized at September 30, 2021 and December 31, 2020; 10,957 and 10,933 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	110	109
Additional paid-in capital	130,628	125,094
Accumulated deficit	(73,692)	(57,993)
Total stockholders’ equity	57,046	67,210
Total liabilities and stockholders’ equity	$ 68,101	$ 79,120