BORE SIZE: 81mmMachined from Wiseco sleeve forgings to offer the same toughness as Wisecos forged pistons. These compressor sleeves are hard anodized and Teflon coated for low friction and prolonged wear resistance. These sleeves have a smooth radius that tapers down to the specific bore size to make installation of any piston a breeze.You will find that these sleeves compress the piston rings smoothly and evenly, greatly reducing the difficulty with installing thin high-performance oil rings. If youve ever broken or bent a ring, these high quality sleeves will be a lifesaver for your shop and come in a large range of sizes.PART# RCS08100