The PowerMax Sand Bag is built from durable woven nylon fabric and is double sealed to hold inner sand tubes securely. Five padded handles are strategically placed for multiple movement planes and versatility.Inner sand bag that is self sealing and marked for references for filling. A quick and convenient method to measure our your weights for sand bag training.Sand bag inserts (sand not included) are designed to be leak proof, and give the ability to adjust weight in each bag. Inner Sand Bag that can hold up to 20lbs. Markings at 10, 15, 20lbs to be filled with coarse sand.