The EXPED backpack line includes both waterproof and weatherproof models. Waterproof means these backpacks keep water out unless submerged in water. Weatherproof means that the fabric and seams are completely waterproof, but zippers and hydration ports are water resistant and not 100% waterproof.

All other backpacks in the EXPED line have coated fabrics to prevent water penetration. These backpacks do not have taped seams. Typically, other features such as durability or weight reduction are the focus of these products and are designed to be used with our waterproof drybags to keep the contents dry.

The torso length is the length of a person's back, measured from the hip to the shoulder, and is an important factor in the fitting process of a backpack.

Depending on the volume of the backpack and its intended use, the suspension system of a backpack becomes a key criterion. Determining back length is not as critical for shorter hikes or everyday backpacks, but is crucial for expedition, trekking and touring backpacks. With these backpacks, the pack weight can only be optimally transferred to the hips if the back length and suspension system are correctly matched.

The center of the hip belt is ideally located on the hip bones (upper edge of the pelvis) and the sacrum to carry most of the load, especially with large internal frame backpacks. There are exceptions where a shorter backpack length is better, such as in alpine situations, because this allows a shorter overall length of the backpack suspension system to allow easier access to the climbing harness.

To determine your back length, use a tape measure to measure the distance from the top of your shoulders to the top of your hip bone (pelvic rim). This is best done by a friend who can properly place and read the tape measure on your back. Any EXPED retailer should also be able to help you determine your back length.