Designed to be a direct fit into the stock thermal bypass housing on your transmission cooler lines, these bypass plugs will keep your transmission running cooler therefore extending transmission life and preventing costly repairs due to a failed thermostat. CNC machined in the U.S.A. from aircraft grade aluminum and fitted with Buna O-rings these bypass plugs are ready to go. These fit many GM vehicles equipped with the 6L80 and 6L90 as well as the 8L90 transmissions, please verify before you buy.