The S25 Bladder is designed for optimum balance and comfort. Its circular bladder is compact, clean and perfect for a streamlined single tank rig. The outer shell of the S25 is made of 1600 denier nylon and 420 denier Polyurethane coated nylon internal bladder. The unit is very streamlined to both reduce drag and make it easier to pass through tight spaces. It is a no bungee design and has a lower left pull relief valve. The S25 has 25 pounds (11.3kg) of lift.