5-ply black silicone straight reducer.

These silicone couplers are made for serious pressure conditions. They have a full 5 layers of high-temperature cording and are 5-5.5 mm thick, giving these couplers a burst pressure of 290 PSI. They are made from pure silicone, giving them an operating range of -40° to 482° F. You will not find a better silicone coupler anywhere.