Cometic, builders cylinder base gasket set. 3-1/2" copper

Copper. Standard bore. Type 'B' gaskets. Builders sets contain 2 gaskets of each thickness .005/ .010/.015/.020".
These are specialty copper base gaskets for mechanics that want to achieve a specific compression ratio.
Type B gasket explained: The 'Type B' gasket is the late type introduced on Evolution XL Sportster models in 1986, and will fit all Evo 883/1200 XL models, but also all 84-99 Evo 1340cc models although the Big Twin cylinder base is a bit larger than the gasket. The 'type B' is the only gasket type that 'The Factory' supplied from 1986 onwards for both Evo Big Twin and Evo XL Sportster models. Both type 'A' and type 'B' have identical inner bore diameter, oil hole and stud hole locations. Gaskets for front & rear cylinder are identical. Only difference between the 'A' & 'B' gaskets is the outside perimeter.