Profile: Precision Fiberglass, Inc. produces R-Box, enclosures and aluminum enclosures. Our R-Box is an insulated fiberglass RPA enclosure to camouflage & protect back flow prevention systems. We offer custom aluminum enclosures for back flow assemblies ranging from _" to 10". The R-Box is constructed using RTM fiberglass reinforced resin that is pigmented with the same color as the gel coat to provide a solid color. A one inch rigid polyurethane foam liner is compression molded to provide a uniform thickness and a consistent cell structure with a secondary bond to the fiberglass cover.