Assets Manufactured for Internal Use, net

12 Months Ended

Dec. 31, 2018

Assets Manufactured for Internal Use, net

Assets Manufactured for Internal Use, net

Note 9. Assets Manufactured for Internal Use, net

Assets manufactured for internal use, included in other assets, are depreciated using the straight-line method over their 10 year estimated useful life. Their components are as follows:

	December 31,
	2018		2017
	(in thousands)
Internal use assets	$	47,509	$	40,366
Construction in process		1,609		301
Total cost		49,118		40,667
Accumulated depreciation		(19,285)		(20,035)
Assets manufactured for internal use, net	$	29,833	$	20,632

These products are used for research and development, training, and customer demonstration purposes.

Depreciation expense was $2.6 million, $2.8 million and $2.4 million for the years ended December 31, 2018, 2017 and 2016, respectively.