aFe Power 59-00005 Magnum FORCE Coupling Kit (4-3/8" x 3-1/2") ID x 2-3/4" L Reducer coupling Reaction Injection Molded (RIM) 100% Polyurethane Standard stainless steel worm-gear #056 & #064 clamps provide tight connections Coupler hose allows for expansion, movement and vibration