These are consumable items when using PCP or HPA setups. These are used to create a seal between your fill probe and a Foster fitting adapter. Use this in place of PTFE tape on 1/8" BSP pressure fittings

Quantity: 1 per pack
Suitable for 1/8" BSP Threads only 
Internal Diameter : 8.5mm (+/- 0.2mm)
Diameter : 16mm (+/- 0.2mm)
Thickness: 2.5mm (+/- 0.2mm)