Detail Size : The outer diameter of the interface is 13mm / 0.5in, and the inner diameter of the interface is 8mm / 0.3in. Easy to Operate : Easy to apply to the head, just tighten it, the billiard cue stick ferrules is easy to operate. Fiber Material : Billiard cue stick ferrules are made of high-quality fiber material, which is and can be used for a long time. Compact Size : Compact, lightweight and lightweight. An ideal substitute for swimming pool pipes, it is an ideal and useful tool accessory. Three Sizes : The size model is 1 inch / 25 mm, 0.8 inch / 18 mm, 0.5 inch / 12.3 mm for your choice. Feature:
1. It is made of fiber material, 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 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 Ferrules
Material: Fiber 
Color: As Pictures Shown 
Outer Interface Diameter: Approx. 13mm/0.5in
Inner Interface Diameter: Approx. 8mm/0.3in.

Package List:
40 x Billiard Cue Stick Ferrules   

Note:
Please check the detailed size on the picture.