King developed Alecular Bearing Material alternative to the traditional tri-metal bearings construction. King bearings have a single deep (.012" - .015") layer of Alecular material, an exclusive alloy of aluminum, tin, copper and other metals, on the steel backing. This gives us superior embedability. With advanced quality control procedures, King is able to maintain rod and main bearing wall thickness tolerances at an amazingly tight plus or minus .0001" -- far tighter than other manufacturers. A manufacturing principle that lets racers and street engine rebuilders save engines with borderline crankshaft endplay situations without additional machining. Precisely-controlled bearing flange length is the secret. King originated this manufacturing technology.