Feature:1. It is made of high quality fiber material, durable and long lasting.2. The outer diameter of the interface is 13mm/0.5in, and the inner diameter of the interface is 8mm/0.3in.3. Compact, portable and lightweight. Nice replacement for pool tube, it is an ideal and helpful tool accessory.4. Size models are 1 inch/25mm 0.8 inch/18mm, 0.5 inch/12.3mm for your choice.5. Easy to apply to rod head, only need to screw on. Easy to use.Specification:Item Type: Billiard Cue Stick FerrulesMaterial: Fiber Color: As Pictures Shown Outer Interface Diameter: Approx. 13mm/0.5inInner Interface Diameter: Approx. 8mm/0.3in. Package List:40 xBilliard Cue Stick Ferrules Note:Please check the detailed size on the picture.