Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (41,505)	$ (37,741)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	2,561	2,145
Stock-based compensation expense	2,300	1,569
Change in fair value of redeemable convertible preferred stock warrants and derivative liability	(235)	(408)
Non-cash lease expense	(249)	(82)
Inventory write-down	537	22
Changes in operating assets and liabilities:
Accounts receivable	(4,804)	(729)
Inventory	(3,580)	(895)
Prepaid expenses and other current assets	(606)	(200)
Accounts payable	2,362	(262)
Accrued compensation	235	1,307
Accrued interest expense	804	866
Deferred revenue	615	182
Other liabilities	707	(672)
Net cash used in operating activities	(40,858)	(34,898)
Cash flows from investing activities:
Purchases of property and equipment	(260)	(224)
Net cash used in investing activities	(260)	(224)
Cash flows from financing activities:
Proceeds from issuance of common stock from the exercise of stock options	3,495	2,051
Proceeds from issuance of note payable, net of issuance costs	0	24,685
Proceeds from the exercise of redeemable convertible preferred stock warrants	858	3,310
Proceeds from issuance of common stock from the initial public offering, net of underwriting discounts, commissions and offering expenses	172,409	0
Net cash provided by financing activities	261,472	106,534
Net increase in cash, cash equivalents, and restricted cash	220,354	71,412
Cash, cash equivalents, and restricted cash- Beginning of period	100,907	42,712
Cash, cash equivalents, and restricted cash - End of period	321,261	114,124
Reconciliation of cash, cash equivalents and restricted cash to balance sheets:
Cash and cash equivalents	320,484	113,347
Restricted cash	777	777
Cash, cash equivalents and restricted cash in balance sheets	321,261	114,124
Supplemental cash flow information
Interest paid	3,566	2,785
Non-cash investing and financing activities
Transfer of evaluation units from inventory to property and equipment, net	(1,227)	1,470
Property and equipment included in accounts payable and accrued expenses	200	200
Deferred offering costs included in accounts payable and other current liabilities	819	0
Series F
Cash flows from financing activities:
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	0	$ 76,488
Series G
Cash flows from financing activities:
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	$ 84,710