FingerTech S3M Timing Pulley - 9T Pitch (distance between tooth centers): 3mm 9 Teeth, Pitch diameter: 8.59mm (.338"), outside diameter: 7.89mm (.313") Belt Width: 4mm or less Includes 4-40 setscrew for fastening to shaft Material: 6061 Aluminum, weight 1.4g (.05oz)