6. Inventory

Inventory consisted of the following:


	As of June 30,		As of December 31,
	2018		2017
Raw materials	$	350	$	616
Work in process		709		322
Finished goods		7,485		875
Total inventory	$	8,544	$	1,813

The aggregate charges related to excess inventory for the three and six months ended June 30, 2018 were immaterial. During the three and six months ended June 30, 2017, the aggregate charges related to excess inventory were $257 and $350, respectively. These expenses were recorded as a component of cost of product revenues.