	September 30,		December 31,
	2020		2019
Work in process	$	3,505	$	2,529
Finished goods		4,213		3,519
Total inventory	$	7,718	$	6,048

	September 30,			December 31,
	2020			2019
Computer equipment and software	$	1,795		$	1,405
Leasehold improvements		89			89
Furniture		36			30
Total property and equipment		1,920			1,524
Less: accumulated depreciation		(1,247	)		(989	)
Total property and equipment - net	$	673		$	535

The Company recorded $0.1 million and $0.1 million of depreciation expense for the three months ended September 30, 2020 and 2019, respectively, and $0.3 million and $0.3 million for nine months ended September 30, 2020 and 2019, respectively.

	September 30,		December 31,
	2020		2019
Payroll-related expenses	$	591	$	780
Engineering services		506		637
Accrued inventory		301		283
Accrued warranty		58		194
Taxes payable		48		72
Professional fees		41		31
Other		17		15
Total accrued liabilities	$	1,562	$	2,012

Customer deposits represent payments received in advance of shipments and fluctuate depending on timing of customer pre-payments and product shipment. Customer deposits were $0.9 million, $0.3 million and $1.4 million as of September 30, 2020, June 30, 2020 and December 31, 2019, respectively. The Company generally expects to recognize revenue from customer deposits during the three month period immediately following the balance sheet date. During the three months ended September 30, 2020, the Company recognized $0.3 million of revenue from the June 30, 2020 customer deposit balance. During the nine months ended September 30, 2020, the Company recognized $1.4 million of revenue from the December 31, 2019 customer deposits balance.