A large, heavy pack of weighs , and of water weighs . The best-made packs may carry up to twice their weight in water; less well-made packs may only carry half their weight in water. The British army bergen backpack, which has a capacity of carrying up to is made from 1000 denier nylon. Backpacks carrying more than usually have waist-belts to help with posture by transferring the weight to the hips. Some experts recommend keeping the equipment's total weight to less than 25% of the hiker's weight.