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.

Effective January 1, 2020, the Company adopted ASU 2016-13. This ASU replaces the incurred loss impairment model with an expected loss impairment model for financial instruments, including accounts receivable. The amendment requires entities to consider forward-looking information to estimate expected credit losses. The Company did not record an adjustment upon adoption of ASU 2016-13.

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 $0.03 million at June 30, 2021 and $0.07 million at December 31, 2020.

The following table summarizes the allowance for credit losses activity during the six months ended June 30, 2021:

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 June 30, 2021 and December 31, 2020 were composed of raw materials, work-in-process and finished goods. The Company had consigned inventory with customers of $0.5 million and $0.3 million at June 30, 2021 and December 31, 2020, 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 $3.8 million at June 30, 2021 and $3.7 million at December 31, 2020.

	June 30, 2021		December 31, 2020
Raw materials	$	5,646	$	5,315
Work-in-process		975		883
Finished goods		5,770		3,786
Inventories, net	$	12,391	$	9,984

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 sales and operating expenses in the condensed consolidated statements of operations. Maintenance and repairs are expensed as incurred.

	June 30, 2021			December 31, 2020
Building	$	6,868		$	6,868
Computers and office equipment		10,309			10,039
Manufacturing and test equipment		16,454			15,394
Furniture and fixtures		1,438			1,437
Leasehold improvements		2,998			2,973
Motor vehicles		20			20
Total property and equipment		38,087			36,731
Less: Accumulated depreciation and amortization		(27,467	)		(25,996	)
Land		1,770			1,770
Property and equipment, net	$	12,390		$	12,505

Depreciation and amortization expense were approximately $0.8 million for each of the three months ended June 30, 2021 and 2020. Depreciation and amortization expense were approximately $ 1.5 million for each of the six months ended June 30, 2021 and 2020, respectively. Amortization for finance leases is included in depreciation and amortization expense. See Note 11 for information related to finance leases.

	June 30, 2021		December 31, 2020
Inventory receipts	$	3,482	$	3,049
Paid time off		1,547		1,028
Payroll and other employee benefits		1,646		1,083
Professional fees and contractors		405		316
Employee stock purchase plan		221		224
Operating leases		450		269
Warranties		284		285
Deferred revenues		305		242
Real estate taxes		156		155
Income and sales taxes		234		185
Customer refunds for estimated returns		205		146
Finance leases		75		68
Restructuring		60		15
Other		384		251
Total	$	9,454	$	7,316

	June 30, 2021		December 31, 2020
Operating leases	$	3,810	$	3,949
Deferred payroll taxes		243		243
Finance leases		117		96
Deferred revenue		65		76
Other		110		23
Total	$	4,345	$	4,387

June 30, 2021

December 31, 2020

Credit loss provision

Credit allowances

Total allowances