The United States military designed MOLLE backpacks to meet the needs of military personnel who have to carry a lot of equipment on their backs. The acronym MOLLE stands for modular lightweight load-carrying equipment, and the packs accommodate different sizes of pouches and other bags to build a better backpack. While these packs are obviously maximally efficient in tactical situations, they are also usable for everyday purposes. In addition, if you prefer not to walk around with camo print gear while in civilian clothes, there are some plain black MOLLE packs available, letting you take advantage of the pack's design while avoiding overt associations with military gear. Many different situations exist in which one of these bags can be useful. For example a MOLLE hydration backpack can make a great accessory for hiking, with its superior ability to carry fear and the availability of a hydration pack right on your back. MOLLE backpacks exist in great numbers on eBay, including the actual backpacks, as well as different packs you can strap on using the PALS webbing on the front of the pack.