The Mares Slide and Lock System (SLS) weight pockets have sturdy zipper closures and are easy to slide into the BCD even when wearing thick gloves. The SLS is the safest system available and come in weight capacities of4 kg and 6 kg (9 lbs. and 13 lbs.) weight capacities. SLS weight pockets will work with block or soft pouch weights. Sturdy zippered pocket for Quantum BCDs Easy to slide into pocket Visual Confirmation of Proper Weight Pouch Insertion Safest system available Easy to use with thick gloves Weight Capacities of small- 4 kg (9 lbs) and large - 6 kg (13 lbs)