The Spectre 4 inch Aluminum Mass Air Flow Sensor Adapter Kit is designed for use with drop-in style mass air flow sensors on 2004 and later vehicles. With an outside diameter measuring 4 inches by 4 inches long, this kit features a polished aluminum tube with ABS components and the necessary hardware. This kit includes 2 flow calibration tubes - 76 millimeter and 89 millimeter, reducing the 4 inch intake system to the correct diameter at the sensor to retain calibration.