Inventories

Inventories are valued at the lower of cost or market. Cost is determined by the first-in, first-out (“FIFO”) method. We establish an allowance for excess and obsolete inventories based on product line changes, the feasibility of substituting parts and the need for supply and replacement parts.



	June 30, 2014			December 31, 2013
	(in thousands)
Raw materials	$	32,750		$	28,592
Work in process	2,267			2,286
Finished goods	2,326			1,841
	37,343			32,719
Less: Allowance for excess and obsolete inventories	(735		)	(579		)
Total, net	$	36,608		$	32,140

The related changes in the allowance for excess and obsolete inventories account are as follows:



	Three months ended				Six months ended
	June 30, 2014		June 30, 2013		June 30, 2014		June 30, 2013
Allowance for excess and obsolete inventories:	(in thousands)
Balance, beginning of period	$	583	$	532	$	579	$	363
Provisions for excess and obsolete inventories	152		5		156		201
Inventories written off	—		—		—		(27		)
Balance, end of period	$	735	$	537	$	735	$	537