CONDENSED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 34,554	$ 40,599
Accounts receivable, net of allowance of $27 and $19, respectively	2,695	2,012
Notes receivable, net of allowance of $9 and $9, respectively	436	444
Inventories	12,449	13,473
Prepaid and other current assets	1,432	1,857
Total current assets	51,566	58,385
Property and equipment, net	734	832
Equipment under lease, net	4,937	3,583
Notes and other receivables, long-term, net of allowance of $6 and $9, respectively	275	452
Intangible assets, net	11,487	12,110
Other assets	3,485	3,758
Total assets	72,484	79,120
Current liabilities:
Accounts payable	2,858	2,481
Accrued liabilities	3,292	4,570
Deferred revenue	1,071	923
Other current liabilities	502	493
Total current liabilities	7,723	8,467
Long-term operating lease liabilities	3,061	3,314
Other long-term liabilities	72	129
Total liabilities	10,856	11,910
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, par value $0.01 per share, 10,000 shares authorized at June 30, 2021 and December 31, 2020; no shares issued and outstanding at June 30, 2021 and December 31, 2020
Common stock, par value $0.01 per share, 150,000 shares authorized at June 30, 2021 and December 31, 2020; 10,957 and 10,933 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	110	109
Additional paid-in capital	129,055	125,094
Accumulated deficit	(67,537)	(57,993)
Total stockholders’ equity	61,628	67,210
Total liabilities and stockholders’ equity	$ 72,484	$ 79,120