Panniers are the bags or containers that hang from the pack saddle on either side of the animal, carrying the equipment, food, and supplies that are the purpose of the packing trip. The best type for a given situation depends on the terrain, the type of load, the duration of the trip, and the user's preference for weight, organization, and durability.
Rigid panniers — typically made of aluminum, fiberglass, or high-density plastic — provide the best protection for fragile contents and are the preferred choice for outfitters carrying photographic equipment, perishable food, or other items that cannot tolerate compression or impact. Their rigid walls make them easy to load without worrying about balance shifting as soft contents settle. The primary disadvantage of rigid panniers is weight.
Soft panniers — made from canvas, nylon, or leather — are lighter, more flexible, and can accommodate irregularly shaped loads that won't fit neatly into a rigid box. Canvas and leather soft panniers have been the traditional choice of packers for generations and remain popular for their durability, repairability, and classic appearance. Modern nylon soft panniers are lighter and waterproof but may be less repairable in the field.