The monstro coupler is designed to fit pipes larger than the standard theatrical battens. CNC machined from solid billet aircraft-grade aluminum, they are perfect for attaching to odd size pipes and tubes. Monstro-Couplers have a narrow size range of application. Monstro coupler is designed with a plus or minus 0.0625" tolerance on their nominal size to ensure that they will fit with the aluminum association pipe and tubing manufacturing tolerances.