Hedman Hedders 21143 Oxygen Sensor Header Reducer Tube Size 2.5 in. Collector Size 3 in. w/Ball And Socket Flanges Mild Steel Oxygen Sensor Header Reducer HEDMAN 21143 3in To 2-1/2in Collector W/O2 Sensor Bung B&S Dimensions in Inches (LxWxH): 6.2 x 6.2 x 4.5