These are designed for lighter weight plastic and FRP piping systems; they have lower spring forces to compress, extend, or offset as compared to heavier models used in metal piping systems. The wide arch also allows a normal flow of the media and reduced buildup. Available in single arch (PRO261R-) or double arch (PRO262R-) in sizes 1.5"-20", and standard lengths of 6" or 8" (depending on size). Various rubber compounds available depending on the media, temperature, etc.; EPDM tube and cover (suffix EE), Neoprene tube and cover (suffix NN), Neoprene cover/Nitrile Tube (NP), Chlorobutyl (BB). This series has lighter weight steel flanges compared to the heavier, standard ones.