Size: Total Length: 28mm / 1.10'; Inner Diameter: 8mm / 0.31', Outside Diameter: 32mm / 1.26' Convenient to install: Easy to install but professional installation is recommended. Chain roller pulley slider complete with duty bearings ready to use. Necessary Function: This chain pulley roller slider is useful and a necessary accessory for most dirt pit bikes, street bikes, motorcycles, ATVs, off-road vehicles, etc. Durable Material: Made of durable rubber and metal material, which is waterproof, hard resistant. Universal Fit: The chain roller guide is fit for most dirt pit bikes, street bikes, motorcycles, ATVs, off-road vehicles, etc.