Inventories, Net and Significant Suppliers (Tables)

12 Months Ended

Dec. 31, 2018

Inventories, net were as follows:



	December 31,
(In thousands)	2018			2017
Raw materials	$	68,834		$	43,638
Components	25,071			16,214
Work in process	5,577			1,847
Finished goods	50,006			105,178
Reserve for excess and obsolete inventory	(5,138		)	(4,288		)
Inventories, net	$	144,350		$	162,589

Changes in Reserve for Excess and Obsolete Inventory

Changes in the reserve for excess and obsolete inventory were as follows:



	Year Ended December 31,
(In thousands)	2018			2017			2016
Balance at beginning of period	$	4,288		$	4,205		$	3,045
Additions charged to costs and expenses ⁽¹⁾	6,702			3,685			3,464
Sell through⁽²⁾	(1,825		)	(1,242		)	(1,116		)
(Write-offs)/Foreign exchange effects	(4,027		)	(2,360		)	(1,188		)
Balance at end of period	$	5,138		$	4,288		$	4,205


⁽¹⁾	The additions charged to costs and expenses do not include inventory directly written-off that was scrapped during production totaling $2.0 million, $0.4 million, and $0.3 million for the years ended December 31, 2018, 2017, and 2016, respectively. These amounts are production waste and are not included in management’s reserve for excess and obsolete inventory.


⁽²⁾	These amounts represent the reversal of reserves associated with inventory items that were sold during the period.

Purchases from Significant Suppliers

We purchase integrated circuits, components and finished goods from multiple sources. Purchases from the following supplier totaled more than 10% of our total inventory purchases:



	Year Ended December 31,
	2018				2017				2016
	$ (thousands)		% of Total Inventory Purchases		$ (thousands)		% of Total Inventory Purchases		$ (thousands)		% of Total Inventory Purchases
Texas Instruments	—	⁽¹⁾	—	⁽¹⁾	$	42,058	10.0	%	$	42,370	11.7	%

⁽¹⁾ Purchases associated with this supplier did not total more than 10% of our total inventory purchases for the indicated period.