High Quality Content by WIKIPEDIA articles! Truck bedliners are coverings that protect the inner-side of a truck bed from damage and can prevent fine-grained cargo such as sand from sifting between the sides and the rear door. Such bedliners are of two types: the plastic drop-in and the "spray on" type."Spray On" or "Spray In" (these terms are used interchangeably in the industry) come in two classes of material: aromatic and aliphatic compounds. Both offer similar protection.Aromatic is generally used for black and darker colors, and is the least expensive option. Aliphatic can be a better option for colors because it is UV stable. It is produced with pure polyurethane, driving cost up approximately 35%. Aliphatic materials can be sprayed in a wide variety of colors, including metallic finishes.