Various types of o-rings for the Aluminum pipes
will fit the Hansen / Chinese & others with the 7/8" header
Sold each
You select which type you need
brown - viton (A75 hardness up to 400*F) - most popular for the manifold
orange - silicone (A70 hardness up to 425*F) - soft - most popular for the aluminum pipe
white - hard teflon (D55 hardness up 500*F) - hard - hard to install - manifold only