Three chambers offer instant support over any obstacle. Waxed Canvas offers a strong, flexible grip and enduring durability. Polymer fill provides stability and balanced weight. Provides strong support for both front and rear. Zippered access pocket to adjust fill volume. Large handle and sling loop for rapid position changes. Birchwood Casey BAG-SSEH Steady-Shot Echo Bag Heavyweight Prefilled Black Wax Canvas Front and Rear Bag.