Harness the speed, improve reaction time and perfect the combination punches that the double boxing ball was made for with exclusive Gyro Balance technology!  Designed to deliver the perfect bounce punch for punch. Engineered with precision and genuine leather construction with double-stitched, welded seams for long-lasting performance. Traditional lace-up closure system for easy access. Includes a pro butyl rubber bladder with special internal balancing for maximum results and industrial rubber top and bottom fastening straps with S-hooks. 

You MUST moisten the needle (preferably with petroleum jelly) before inserting it into the bladder. This will prevent small cracks in the inflation valve and blowing out the bag.