TrackOne silicone couplers are made of reinforced silicone and use 4 ply design for strength.? Transition couplers designed to connect two different size pipes. Features: Reinforced Silicone 4 Ply Available in multiple diameters, length, and angles Diameter - 2.5" to 4" Angles - Straight, Transition, 45 Degree, 90 Degree?