PME2118 Nexelite® 18"W x 21"D Replacement Plastic Mat, End Mat. Nexelite® polymer composition shelf mats have a modular design allowing easy removal for cleaning. They have a vented open grid surface that is smooth and crevice-free. Polymer material will never dent, chip, rust or corrode. The width and depth of your shelf will determine the number of center and/or end panels you need to purchase. For example: a Nexelite® Shelf measuring 42"W x 18"D would require (1) 12"W x 18"D Center Panel and (2) 15"W x 18"D End Panels. , Lot of 1