Accounts receivable are recorded at invoiced amounts with standard net terms that range between 30 and 90 days. The Company extends credit to its customers based on an evaluation of a customer’s financial condition and collateral is generally not required. The Company records reserves for credit losses and credit allowances that reduce the value of accounts receivable to fair value.

The Company is exposed to credit losses primarily through the sale of products. The Company’s expected loss methodology for accounts receivable is developed using historical collection experience, current and future economic market conditions, and a review of the current status of customers’ trade accounts receivable. Due to the short-term nature of accounts receivable, the estimate of amount of accounts receivable that may not be collected is based on aging of the account receivable balances and the financial condition of customers. Additionally, specific allowance amounts are established to record the appropriate provision for customers that have a higher probability of default. The Company’s monitoring activities include timely account reconciliation, dispute resolution, payment confirmation, consideration of customers' financial condition and macroeconomic conditions. Balances are written off when determined to be uncollectible. The Company’s allowance for credit losses was $16 at March 31, 2022 and $26 at December 31, 2021.

The following table summarizes the allowance for credit losses activity during the three months ended March 31, 2022:

Inventories are stated at the lower of cost or net realizable value and include material, labor and overhead costs using the first-in, first-out method of costing. Inventories as of March 31, 2022 and December 31, 2021 were composed of raw materials, work-in-process and finished goods. The Company had consigned inventory with customers of $0.5 million and $0.4 million at March 31, 2022 and December 31, 2021, respectively. The Company records allowances to reduce the value of inventory to the lower of cost or net realizable value, including allowances for excess and obsolete inventory. Reserves for excess inventory are calculated based on an estimate of inventory in excess of normal and planned usage. Obsolete reserves are based on the identification of inventory where the carrying value is above net realizable value. The allowance for inventory losses was $3.4 million at March 31, 2022 and $4.1 million at December 31, 2021.

	March 31, 2022		December 31, 2021
Raw materials	$	5,879	$	6,171
Work-in-process		808		690
Finished goods		6,165		6,830
Inventories, net	$	12,852	$	13,691

Prepaid assets are stated at cost and are amortized over the useful lives (up to one year) of the assets.

Property and equipment are stated at cost and are depreciated using the straight-line method over the estimated useful lives of the assets. The Company depreciates computer equipment and software licenses over three to five years, office equipment, manufacturing

and test equipment, and motor vehicles over five years, furniture and fixtures over seven years, and buildings over 30 years. Leasehold improvements are amortized over the shorter of the corresponding lease term or useful life. Depreciation expense and gains and losses on the disposal of property and equipment are included in cost of revenues and operating expenses in the condensed consolidated statements of operations. Maintenance and repairs are expensed as incurred.

	March 31, 2022			December 31, 2021
Building	$	6,922		$	6,892
Computers and office equipment		10,474			10,604
Manufacturing and test equipment		16,536			16,305
Furniture and fixtures		1,460			1,455
Leasehold improvements		3,012			3,021
Motor vehicles		20			20
Total property and equipment		38,424			38,297
Less: Accumulated depreciation and amortization		(28,704	)		(28,118	)
Land		1,770			1,770
Property and equipment, net	$	11,490		$	11,949

Depreciation and amortization expense was approximately $0.8 million and $0.7 million for the three months ended March 31, 2022 and 2021, respectively. Amortization for finance leases is included in depreciation and amortization expense. See Note 11 for information related to finance leases.

	March 31, 2022		December 31, 2021
Inventory receipts	$	2,704	$	4,302
Paid time off		1,452		1,284
Payroll and other employee benefits		1,284		2,266
Deferred revenues		625		538
Employee stock purchase plan		503		253
Operating leases		495		475
Income and sales taxes		433		415
Professional fees and contractors		360		233
Warranties		253		257
Customer refunds for estimated returns		232		248
Real estate taxes		195		156
Finance leases		53		62
Restructuring		0		368
Other		364		260
Total	$	8,953	$	11,117

	March 31, 2022		December 31, 2021
Operating leases	$	3,463	$	3,600
Finance leases		81		92
Deferred revenue		183		181
Other		93		126
Total	$	3,820	$	3,999

March 31, 2022

December 31, 2021

Credit loss provision

Credit allowances

Total allowances