Insert For Heavy-Duty Half Coupling - 2 1/2in. Dia. Go to amazon.com Related posts Top 7 reducer coupling insert FeatureRecessed Diameter: 1in.Six Fingers: 7/16in.W x 5/8in. Thick DescriptionL/AL099/100 Spider Sox. Material Type: Buna-N, Outside Diameter (in.): 2 1/2