Mishimoto
Mishimoto 3.5in to 4in Silicone Transition Coupler, Blue MMCP-3540BL
CouplerMishimoto 3.5in to 4in Silicone Transition Coupler, BlueMishimoto has developed a silicone transition coupler that measures 3.5in to 4in. Available in black, blue, and red.