Tool works on OEM electrical connectors used on trucks and equipment such as Caterpillar, Kenworth, Peterbuilt, Freightliner, Mack and more. Also used on some Harley Davidson connectors. Tool has three sizes of slotted tubes for working on different sizes of Deutsch terminals. Slotted tubes are made out of stainless steel which work and last longer than plastic disconnect tools. To use, slide appropriate size slotted tube over wire. Push tool into grommet, it will bottom out on the Deutsch terminal. Do not twist tool. Pull the wire terminal out of the connector.