Balance Sheet Components

3 Months Ended

Mar. 31, 2021

5. Balance Sheet Components

Investments

The fair value of the Company's available-for-sale investments as of March 31, 2021 and December 31, 2020 are as follows (in thousands):


	March 31, 2021
			Gross Unrealized				Estimated
	Amortized Cost		Gains		Losses		Fair Value
Money market funds	$	93,977	$	—	$	—	$	93,977
Commercial paper		13,292		—		—		13,292
Corporate bonds/notes		7,905		—		(1)		7,904
U.S. government securities		20,294		7		—		20,301
	$	135,468	$	7	$	(1)	$	135,474
Classified as:
Cash equivalents							$	93,977
Short-term investments								41,497
							$	135,474


	December 31, 2020
			Gross Unrealized				Estimated
	Amortized Cost		Gains		Losses		Fair Value
Money market funds	$	60,295	$	—	$	—	$	60,295
Commercial paper		39,577		—		—		39,577
Corporate bonds/notes		7,970		—		(1)		7,969
U.S. government securities		38,430		42		(2)		38,470
	$	146,272	$	42	$	(3)	$	146,311
Classified as:
Cash equivalents							$	68,295
Short-term investments								78,016
							$	146,311

All of the Company’s cash equivalents and short-term investments mature within one year as of March 31, 2021 and December 31, 2020. Available-for-sale investments held as of March 31, 2021 had a weighted average days to maturity of 136 days.

The following table presents the Company's available-for-sale investments that were in an unrealized loss position as of March 31, 2021 and December 31, 2020 (in thousands):


	March 31, 2021				December 31, 2020
	Less than 12 months				Less than 12 months
Assets:	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate bonds/notes	$	7,845	$	(1)	$	5,369	$	(1)
U.S. government securities		—		—		10,128		(2)
	$	7,845	$	(1)	$	15,497	$	(3)

Inventories

Components of inventories were as follows (in thousands):


	March 31,		December 31,
	2021		2020
Raw materials	$	2,208	$	1,785
Finished products		10,369		10,599
		12,577		12,384
Less: Reserve for excess and obsolete		(617)		(2,395)
	$	11,960	$	9,989

As of March 31, 2021 and December 31, 2020, there were no work-in-process inventories. The reserve for excess and obsolete inventory at March 31, 2021 and December 31, 2020, included $573,000 and $2,377,000, respectively, associated with the Company's voluntary product recall.

Accrued Liabilities

Accrued liabilities consist of the following (in thousands):



	March 31,		December 31,
	2021		2020
Accrued payroll and related expenses	$	8,118	$	9,573
Provision for sales returns		639		820
Accrued professional services		1,144		2,520
Recall replacement obligation		541		1,696
Operating lease liability		872		850
Accrued royalty expense		571		518
Deferred revenue		536		206
Accrued travel expenses		357		237
Accrued clinical expenses		119		113
Accrued other expenses		394		424
Total	$	13,291	$	16,957