Wiseco RCS40400 4.040in Black Anodized Piston Ring Compressor SleeveWiseco RCS40400 4. 040in Black Anodized Piston Ring Compressor Sleeve Wiseco ring compressor sleeves are forged in house in the USA and are a precision solution to assist in your high performance engine build. Hard anodized and Teflon coated for low friction and prolonged wear resistance Sleeves have smooth radius that tapers down to the specific bore size Compresses the piston rings smoothly and evenly Greatly reduces difficulty of installing high