These are needed when using a HHO system or test pipe. They are also used to tilt your vehicle for better gas mileage. Are very easy to install by unscrewing your O2 sensor from your exhaust then screw your sensor into the extender then screw both pieces back into your exhaust. The extension has a 7/8 hex head which is the same size as most O2 sensors and this makes them easier to install unlike straight sided extensions. Fits most sensors with a 1/2 inch diameter tip. The size of the extensions is X 1.50 and are 1.253 inches long and are drilled to 0.5175 inches. If you need more space, you can stack them and a conical seat without washer required. Model: x 1.5 Universal for any 18mm thread size Straight Bolt-On, modification required Color: Silver Material: Metal Package Contents: 1 x Sensor Extension Connectors Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in a little different from the