The Pump Pillow is designed to extend your reach and eliminate space in the body. As a result, the reduction of muscle strain makes your shot placement more accurate! The Modular version allows the flexibility of controlling how much and what kind of fill is in the bag. We now manufacture individual inner bags, up to 5 for the Pump Pillow, that can be used to fill the Pump Pillow to various level of tightness. You can also fill the outer shell with your own articles such as, rain gear or jackets.