3.	Balance Sheet Components

Property and Equipment

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

	March 31, 2016			December 31, 2015
	(Unaudited)
Prototype	$	6,476		$	6,492
Machinery and equipment		8,871			7,128
Leasehold improvements		1,524			1,532
Furniture and fixtures		359			350
Software		866			832
Construction in progress		4,506			1,851
Property and equipment, gross		22,602			18,185
Less: accumulated depreciation and amortization		(11,189	)		(10,879	)
Property and equipment, net	$	11,413		$	7,306

Depreciation and amortization expense related to property and equipment were $326 thousand and $246 thousand during the three months ended March 31, 2016 and 2015, respectively.

Intangible Assets

Intangible assets consisted of the following (in thousands):

	March 31, 2016			December 31, 2015
	(Unaudited)
License cost	$	500		$	500
Patents		104			104
Intangible assets, gross	$	604		$	604
Accumulated amortization		(450	)		(404	)
Intangible assets, net	$	154		$	200

Intangible amortization expense were $46 thousand and $42 thousand during the three months ended March 31, 2016 and 2015, respectively, which were recorded in general and administrative expenses in the condensed consolidated statements of operations.

At March 31, 2016, the estimated future amortization expense of purchased intangible assets was as follows (in thousands):

Year Ending December 31,	Estimated Future Amortization Expense
	(Unaudited)
The remainder of 2016	$	69
2017		18
2018		18
2019		18
2020		18
2021		13
Thereafter		—
Total amortization expense	$	154

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	March 31, 2016		December 31, 2015
	(Unaudited)
Accrued payroll and related benefits	$	2,205	$	1,938
Accrued accounts payable		1,055		1,880
Sales tax and medical device excise tax payable		343		219
Accrued legal and accounting		813		857
Other		693		519
Total accrued liabilities	$	5,109	$	5,413

Deferred Revenue

Deferred revenue consisted of the following (in thousands):

	March 31, 2016			December 31, 2015
	(Unaudited)
Deferred revenue:
Product	$	5,050		$	5,050
Services		1,268			911
Total deferred revenue		6,318			5,961
Less: current portion of deferred revenue		(5,889	)		(5,616	)
Noncurrent portion of deferred revenue	$	429		$	345