A battery or accessory pouch made of quality Cordura. Its purpose is to hold a battery for an NVG or an action camera. There is a large inner velcro for attachment to the helmet, so it will hold tight.
However, it's not just a pocket. It is a platform with a part leading to the top of the head, where is a rubber band to hold a cable or other necessary stuff.
You can use this pouch also for a weight to make your helmet more balanced. In comparison with the Mk.1 model, this one has slightly different proportions of the pocket, which is also more open on the top.
Pouch proportions: 135 x 75x 35 mm