(4) Inventories

Inventories are valued at the lower of cost (using either the first-in, first-out (“FIFO”) or average cost methods) or net realizable value. The Company evaluates and adjusts as necessary its excess and obsolescence reserve on a quarterly basis. Excess inventories are quantities of items that exceed anticipated sales or usage for a reasonable period. The Company has guidelines for calculating provisions for excess inventories based on the number of months of inventories on-hand compared to anticipated sales or usage. Management uses its judgment to forecast sales or usage and to determine what constitutes a reasonable period. Inventory cost includes material, labor and overhead. Inventories consisted of the following:


	March 31,		December 31,
	2019		2018
Raw materials	$	60,967	$	54,382
Work-in-progress		5,610		4,710
Finished goods		25,585		20,186
Total inventories, net	$	92,162	$	79,278

Inventory valued using the FIFO method was $76,877 and $64,745 at March 31, 2019 and December 31, 2018, respectively. Inventory valued using the average cost method was $15,285 and $14,533 at March 31, 2019 and December 31, 2018, respectively.