For External Halyard Poles up to 3 1/2 in dia. Treaded Type, Stationary with Double Pulley. Molded fiberglass construction with 1 1/2 in. outside diameter cast nylon pulleys on 1/4 in. stainless steel axles. The top of the truck is designed to accept an ornament with a spindle threading of 1/2 in. -13NC as standard but can be supplied with other sizes of threading if desired. The aluminum spindle is threaded 1 1/4 in. NPT. The recommended maximum halyard diameter is 5/16 in.