A guide block to drill guide holes in the plastic blocks for the slider frame aft pins. This is tool is for the Bill Duffy slider canopy installation procedure, a multiple builder. Drill the canopy guide blocks firstly then set the canopy in position. His words "Best fitting canopy yet, the blocks are great, pins slide in perfectly." Made out of ASA plastic. If you would like to talk to Bill and be enlightened about sliding canopys, give him a call at: 513-304- zero two nine four. Instructions: Square the canopy front and back, left and right with the blocks clamped down, cut the front to match rear height. Set with clamps, JB weld epoxy in position, remove blocks, drill to fuse, counter sink blocks for bolts. Mount everything up and watch your canopy lock in to a perfectly secure position.