King offers 3 levels of rod bearings for use in OE Stock,High Performance, and Extreme Performance applications. Kingconnecting rod bearings are sold in engine sets.CP Series, AM Series amp ampamp SI Series BearingsKing CP Series, AM Series amp ampamp SI Series bearings arerecommended for OE applications. CP Series beartings arecopper lead on steel Tri Metal with a .001 copper lead tinoverplate. AM Series bearings are aluminum copper tin plus Alloy onhigh strength steel Bi Metal . SI Series bearing