Sandbag training can provide a non-conventional method for building muscle, boosting overall strength and burning gobs of fat and calories. The secret to sandbag training lies in the moving and shifting of the load within the sandbag. Due to the nature of sandbags, more muscles must work harder to compensate for the instability of the weight. More muscles worked equals more calories burned and greater gains in strength both in the major muscle groups as well as minor muscle groups and the core. Sandbag training can provide a much needed break from a standard weight lifting routine while keeping the body challenged and on its toes for maximum performance. If you are looking for something challenging and something different; sandbag training may be the way to reach a whole new level of strength and fitness. The Perform Better Ultimate sandbag is one of the most versatile and challenging exercise tools available. With adjustable resistance and ease of use, the Ultimate sandbag is sure to become one of your “go-to” pieces of training equipment. Heavy-Duty Outer Shell. The Ultimate sandbag features an outer shell that contains inner bags. The heavy-duty outer shell uses both zippers as well as buttons to enclose the inner bags. This outer shell keeps the weight of the inner bags secure, and keeps the sand where it belongs-inside the bag. Inner Filler Bags. Contained inside the secure outer shell are the inner bags that get filled with sand. The amount of sand in the bags can be easily and quickly adjusted to add or remove resistance from your conditioning workout. The use of a multilayer bag system keeps sand secure and prevents mess.