S&S Cycle 14mm Compression Release Hole Plug The S&S Cycle 14mm Compression Release Hole Plug offers a perfect solution for engines with machined heads not utilizing compression releases. It provides a secure seal, compatible with any style of rocker cover, ensuring leak-free performance. Features: If cylinder heads are machined for S&S compression releases, but compression releases are not used, this special plug must be installed to seal the machined hole Can be used with any style rocker cover Sold individually Made in the USA Note: Not for use on OEM heads.