Black Silicone Coolant Bypass Cap, 1 3/4 inch ID 20730 A washer is included with

A washer is included with this adapter

The 4-ply reinforcement results in a 5mm wall thickness (86mm / 3 3/8" and 80mm / 3 1/8" OD) and a working pressure rating over 20 psi (100 psi burst pressure)

It is designed specifically for connecting a 4" (102mm) OD metal intake pipe to a 3 1/2" (89mm) OD pipe

5mm wall thickness (41mm / 1 5/8" OD) and a working pressure rating over 27 psi (135 psi burst pressure)

Black Silicone Coolant Bypass Cap, 1 3/4 inch ID 20730 A washer is included withThis cap features the same water and coolant compatible silicone rubber formulation as our silicone coolant hoses. It is designed for capping off coolant bypass or vacuum fittings, but it can also be used to protect fittings in storage. This size has a 45mm (1 3 4") ID, 53mm (2 1 16") OD and measures 38mm (1 1 2") Long overall with a 30mm depth. Maximum temperature 392 F (200 C). Operating pressure rating 14 psi. Black silicone rubber only. Sold