ProMaster's Long Lens Plate is used to balance long lenses and heavy or awkward camera rigs on gimbal heads, ball heads, and cine/video heads. The extra length of this plate allows it to slide back and forth in a dovetail head (arca-type) until the proper balance point is found. Then it is locked in place for the best stability when using movements on the head.
This long lens plate can also be used as an anti-twist remedy for lenses and cameras that have two threaded connection ports on their bottom side. The plate includes both a 1/4"-20 and 3/8"-16 connection bolt. Many long lenses have two tripod ports, with each being one of these sizes. By connection both bolts to your lens or camera you will drastically improve stability and eliminate any possible twisting of the lens or camera on the plate.