(6) Inventories

Inventories are valued at the lower of cost (principally on a standard cost basis which approximates the first-in, first-out method) or net realizable value. Raw materials and supplies principally consist of raw steel, glass, paint, vinyl and other assembly components used in manufacturing and remanufacturing processes and, to a lesser extent, parts used for internal maintenance and ancillary items held for sale in our Tank & Pump Solutions segment. Work-in-process primarily represents partially assembled units. Finished units primarily represent purchased or assembled containers held in inventory until the container is either sold as is, remanufactured and sold, or remanufactured and deployed as rental fleet. Inventories at September 30, 2018 and December 31, 2017 consisted of the following:

	September 30, 2018		December 31, 2017
	(In thousands)
Raw materials and supplies	$	9,892	$	11,732
Work-in-process		—		50
Finished units		3,552		3,889
Inventories	$	13,444	$	15,671