The following table summarizes the Company’s principal contractual commitments, excluding operating leases, as of September 30, 2020 (in thousands):

	Purchase Commitments		Other Contractual Commitments		Total
2020 (remaining three months)	$	12,384	$	206	$	12,590
2021		1,502		8		1,510
Total	$	13,886	$	214	$	14,100

Purchase commitments for inventories are highly dependent upon forecasts of customer demand. Due to the uncertainty in demand from its customers, the Company may have to change, reschedule, or cancel purchases or purchase orders from its suppliers. These changes may lead to vendor cancellation charges on these purchases or contractual commitments.

The following table summarizes the Company’s warranty accrual account activity during the nine months ended September 30, 2020 and 2019:

	Nine Months Ended September 30,
	2020			2019
Balance at beginning of period	$	407		$	316
Warranty accrual acquired in acquisition		—			90
Accruals for warranties charged to expense		125			177
Cost of warranty claims		(58	)		(18	)
Balance at end of period	$	474		$	565

The Company provides warranties on certain product sales for periods ranging from 12 to 36 months, and allowances for estimated warranty costs are recorded during the period of sale. The determination of such allowances requires the Company to make estimates of product return rates and expected costs to repair or to replace the products under warranty. The Company currently establishes warranty reserves based on historical warranty costs for each product line combined with liability estimates based on the prior 12 months’ sales activities. If actual return rates and/or repair and replacement costs differ significantly from the Company’s estimates, adjustments to recognize additional cost of sales may be required in future periods.