The Nucleus is a new addition to the vest lineup and features our Ergo X Harness, which is a patented harness system defined by its distinct shape and fit. The Ergo X Harness keeps the weight and pressure points off of the soft tissue areas resulting in better blood flow and cooling. The front pocket is double layered for added capacity. The back compartment is layered with sweat proof fabrics to keep contents safe from moisture and sweat. One side features an on-the-go accessible magnetic pocket for quick access. The other side has an added zippered compartment for items you wish to keep more secure. The bottom of this compartment has been reinforced with a dual layer of nylon at the stress point for durability. This pack features the UltrAcool Light Mesh for added durability and breathability. The Nucleus utilizes the Max02 Waist closure system which provides an incredible fit with easy adjustment, but also allows for an uninterrupted natural breathing pattern. One size fits most.