A set of pouches that sits under your rucksack on your hips that holds things like ammo and water bottles. Normally weighs about 10kg
sounds like a utility belt to me.
Do you carry ammo and water bottles during your training exercises?
it is a bit fancier than a utility belt as it has shoulder straps.
Normally carry empty magazines and then make up the rest of the weight with water and other random items that will fit it to make the kit up to the weight required.