A map pouch with a zipper is on top of the tank bag. This tank bag can be used as a single map pouch (4,5cm high) but also as a tank bag when you open the zipper on the side (13,5cm high) with about 7 Litre capacity. W = 24cm; L = 28cm.
The tank bag will stay in place with 4 suckers (vacuum suction). You can carry the tank bag easily with the handle or with the shoulder strap. Waterproof material.
But when you ride in extreme continuous rain a protective cover is very recommended as water can seep in the zips.