The XDOG™ Weighted Drag Bag for dogs helps by building explosive leg drive and stronger body muscle with resistance training and workout. The weighted drag bags feature removable weights allowing you to adjust the towing resistance. The drag bags use sand (not included) as weights. The bags can easily be filled with sand allowing you to increase or decrease weight resistance down the ounce for precise and safe weight pulling. To be used only with the XDOG™ Vest.