5. Balance Sheet Components

Inventory

Inventory and Printed Circuit Board Assemblies (“PCBAs”), which are recorded as other assets as they are used many times over a period longer than one year on average, consisted of the following (in thousands):

	September 30, 2018		December 31, 2017
Raw materials	$	999	$	1,103
Finished goods		3,630		3,830
Total	$	4,629	$	4,933

Classified as:
Inventory	$	2,320	$	1,683
Other assets		2,309		3,250
Total	$	4,629	$	4,933

Amounts reported as other assets are comprised of the PCBA costs that are included in both raw materials and finished goods totals above.

Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):


	September 30,			December 31,
	2018			2017
Laboratory and manufacturing equipment	$	2,373		$	1,994
Computer equipment and software		1,049			1,015
Furniture and fixtures		925			953
Leasehold improvements		726			726
Internal-use software		7,807			4,598
Total property and equipment, gross		12,880			9,286
Less: accumulated depreciation and amortization		(4,630	)		(3,065	)
Total property and equipment, net	$	8,250		$	6,221

Depreciation and amortization expense was $0.6 million and $1.7 million for the three and nine months ended September 30 2018, respectively, and $0.5 million and $1.1 million for the three and nine months ended September 30, 2017, respectively.

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	September 30,		December 31,
	2018		2017
Accrued vacation	$	2,619	$	2,081
Accrued payroll and related expenses		10,635		9,361
Accrued ESPP contributions		1,397		275
Accrued professional services fees		705		1,041
Claims payable		2,374		1,375
Other		1,448		1,511
Total accrued liabilities	$	19,178	$	15,644

Amounts related to Accrued ESPP contributions as of December 31, 2017 have been reclassified from Other for comparability purposes.