CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
CURRENT ASSETS
Cash and cash equivalents	$ 25,120	$ 22,408
Short-term investments	97,103	0
Accounts receivable, net of allowance for doubtful accounts of $263 and $268 at December 31, 2018 and 2017, respectively	8,486	7,416
Inventory	3,343	2,553
Prepaid expenses and other current assets	1,990	1,252
Total current assets	136,042	33,629
Property and equipment, net	2,154	1,896
Other non-current assets	325	309
TOTAL ASSETS	138,521	35,834
CURRENT LIABILITIES
Accounts payable	2,146	1,814
Accrued liabilities and other	6,860	5,724
Total current liabilities	9,006	7,538
Redeemable convertible preferred stock warrants	0	422
Long-term borrowings	38,963	38,704
Other long-term liabilities	360	0
TOTAL LIABILITIES	48,329	46,664
Commitments and contingencies
Redeemable convertible preferred stock, $0.0001 par value;
Redeemable convertible preferred stock; Authorized: 0 and 12,104,749 shares at December 30, 2018 and December 31, 2017; issued and outstanding: 0 and 11,871,578 shares at December 30, 2018 and December 31, 2017; (Liquidation preference of $0 and $119,194 at December 30, 2018 and December 31, 2017).	0	118,548
STOCKHOLDERS’ EQUITY (DEFICIT)
Preferred stock, $0.0001 par value; Authorized: 5,000,000 and 0 shares at December 31, 2018 and 2017, respectively; no shares issued and outstanding as of December 31, 2018 and 2017.	0	0
Common stock, $0.0001 par value; Authorized: 100,000,000 and 19,333,333 shares at December 31, 2018 and 2017, respectively; issued and outstanding: 24,450,757 and 3,603,140 shares, at December 31, 2018 and 2017, respectively.	3	1
Additional paid-in capital	246,927	9,943
Accumulated other comprehensive income	439	402
Accumulated deficit	(157,177)	(139,724)
TOTAL STOCKHOLDERS’ EQUITY (DEFICIT)	90,192	(129,378)
TOTAL LIABILITIES, REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT)	$ 138,521	$ 35,834