Equipment with an RB suffix, meaning Rainproof type 3R construction, uses the bolt-on hubs listed below. RB devices will accept 3/4 in through 2-1/2 in bolt-on hubs without the use of reducers. Off-center conduit thread openings and elongated mounting holes provide quick and easy adjustment to eliminate costly conduit offsets and bends. Hubs are suitable for use with conduit having ANSI standard taper pipe thread.