Only Fel-Pro® replacement transmission pan gaskets are made of Fel-CoPrene® synthetic rubber. Fel-CoPrene offers a longer life than cork-rubber construction and it doesn’t shrink or wick fluid like cork. Fel-CoPrene doesn’t compress. Instead, it seals by deforming when clamped, and retains positive contact pressure against the castings.
 
Sometimes large, flexible gaskets, like a transmission pan gasket, can be difficult to install. Federal-Mogul engineers developed a unique way to speed installation of Fel-CoPrene transmission pan gaskets and provide a more effective seal: Hole-Locks™. Fel-Pro transmission pan gaskets feature this exclusive Hole-Lock design to help relieve the frustration that usually comes with installing a transmission pan gasket.

The Hole-Lock design features bolt holes in the gasket that are made slightly smaller than the bolts themselves. The design holds the gasket and bolts in place as the transmission pan is installed. This feature also eliminates the need to use contact adhesive on the pan gasket, which would damage the transmission if it got inside the casing.