They come in several forms, including ladder-type, perforated, and wire mesh (also known as basket trays), each tailored to different environments and cable loads. Each cable tray type performs a different function and comes in various materials such as aluminum, galvanized steel, and FRP. What is Cable Tray? A cable tray is a unit, or set of units. FRP/GRP (fiberglass reinforced plastic) cable trays are products that set the industry standard for cable support systems worldwide. Designed for maximum load capacity in their class, they provide high resistance. FRP Cable Trays are non-metallic support systems for routing electrical and data cables in industrial and commercial facilities. It is available with a ventilated or solid bottom.