Pipe plug

A pipe-end plug designed to wedge into the interior of a (1", 25 mm ID) pipe. A 1/4" (6 mm) hex-head bolt is used to pull the opposing wedges into each other and expanding the plug. I'm using this to protect a tarp which is placed over the pipe-end. There is a hexagonal recess for a hex nut in the wedge and a cylindrical recess in the cap for a socket wrench. Would a cap be better and simpler? I don't think so, this tarp has been exposed to 70 mph (112 km/h) wind. Strange and forceful thi