Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 7,286	$ 10,694
Accounts receivable, net of allowances of $270 and $93	20,106	26,764
Inventories	12,822	8,915
Prepaid expenses and other current assets	1,190	1,289
Total current assets	41,404	47,662
Property, plant and equipment, net	71,988	76,067
Other long-term assets	79	86
Total assets	113,471	123,815
Current liabilities:
Accounts payable	8,395	10,653
Accrued expenses	4,710	5,862
Revolving line of credit	3,750	3,750
Deferred revenue	1,540	1,304
Total current liabilities	18,395	21,569
Deferred rent	1,235	1,303
Prepayment liability	3,989
Deferred revenue long-term	927
Total liabilities	24,546	22,872
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.00001 par value; 5,000,000 shares authorized, no shares issued and outstanding at June 30, 2018 and December 31, 2017
Common stock, $0.00001 par value; 125,000,000 shares authorized, 23,940,315 and 23,643,189 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	0	0
Additional paid-in capital	539,870	538,088
Accumulated deficit	(450,945)	(437,145)
Total stockholders’ equity	88,925	100,943
Total liabilities and stockholders’ equity	$ 113,471	$ 123,815