Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statements of Operations
Revenues, net	$ 1,287		$ 2,587
Cost of product revenues	2,711		5,017
Gross profit (loss)	(1,424)		(2,430)
Operating expenses:
Research and development	1,593	$ 3,663	4,568	$ 10,488
Selling and marketing	9,386	7,723	30,263	12,616
General and administrative	3,371	3,270	11,386	9,208
Total operating expenses	14,350	14,656	46,217	32,312
Loss from operations	(15,774)	(14,656)	(48,647)	(32,312)
Other income (expense)
Interest income	1	37	24	284
Interest expense	(999)	(905)	(2,914)	(2,205)
Total other income (expense), net	(998)	(868)	(2,890)	(1,921)
Loss before benefit from income taxes	(16,772)	(15,524)	(51,537)	(34,233)
Net loss	$ (16,772)	$ (15,524)	$ (51,537)	$ (34,233)
Net loss per share (basic) (in dollars per share)	$ (0.18)	$ (0.18)	$ (0.57)	$ (0.41)
Net loss per share (diluted) (in dollars per share)	$ (0.18)	$ (0.18)	$ (0.57)	$ (0.41)
Weighted-average common shares (basic) (in shares)	93,757,215	87,350,505	90,048,183	83,754,550
Weighted-average common shares (diluted) (in shares)	93,757,215	87,350,505	90,048,183	83,754,550
Comprehensive loss:
Net loss	$ (16,772)	$ (15,524)	$ (51,537)	$ (34,233)
Other comprehensive income:
Unrealized loss on marketable securities		1	(3)	11
Comprehensive loss	$ (16,772)	$ (15,523)	$ (51,540)	$ (34,222)