Made of hard fuel resistant plastic with 2 x fuel pipes- one is a one way non leak breather and the other can be connected to the bikes tank breather. Doing this causes the tanks natural vacuum to draw over the fuel from the hebo tank attached to your forks. This way you use the 1.1litres before your tank level starts dropping.
Or alternatively you can use it as a fuel store so you always have a litre handy.
Ideal for SSDT