Chev Billet Block Adapter -12 Male Gen IV & Earlier, Black SY228-90556-12BChev Billet Block Adapter 12 Male Gen IV & Earlier, Black SY228 90556 12B 228 90556 12B Designed to facilitate mounting a remote oil filter on most small block or big block Chevy engine (except Mark IV or later blocks with shallow mounting pad), System 1's highly acclaimed adapter seals at the filter mounting pad where the cast filter bypass adapter was. Comes with choice of AN 10 or AN 12 fittings and a pair of 5 16 18 O ringed 12 point mounting