Cheap silicone couplers blow off under boost. Spulen's don't. 4-ply reinforced, 4mm thick, tested to over 60 psi in real street and track conditions. If you're building a charge pipe setup, running a custom intake, or replacing a failed OEM coupler with something that'll actually hold, this is the one. 2" (51mm) to 2.5" (63mm) inner diameter, 3" (76mm) length.