1x 1/2'' Drive x 27mm (12 points) pressure sending unit socket; Designed for the removal and installation of oxygen sensors, pressure sending units, and vacuum switches equipped with wires or vacuum tubes Including 78 Short low Profile O2 Oxygen Sensor Socket, 78 Universal Oxygen Sensor Socke 78 Universal Vacuum Switch PVS, TVS Socket Tool. Including 1, 116, 1316 Sending Unit Socket, 1116 GM Thermal Switch Socket Made of High Strength CRV Steel and solid cast steel construction for strength and durability Finished with Black Oxide to prevent rust and corrosion Use one of the socket wrenches to turn and loosen the sensor, then clean the manifold threads with the thread chaser; Using the crowfoot socket to initially loosen the sensor as it generates more torque, then use the other socket once the sensor is free