Inner diameter 18mm Outer diameter 29mm Please choose that suits you 6061 aviation aluminum, strong pressure resistance under water Conversion head for yoke to 8mm quick inflation connector for easy inflation<br><br>Specification: Product Name: For YOKE to 8mm quick inflation connector Outer diameter: 29mm Inner diameter: 18mm Air hole: 12.5mm Total length: 55cm Ulti mate pressure of air pipe: Less than 60MPA Ulti mate pressure of connector:Less than 30MPA Colour:black Material:aluminum<br><br>Package Contents: 1 x quick inflation connector<br><br>Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.