Heavy duty, triple stitched soft coveringnAbsorbs impactnAll sizes are 14-Inch diameter and red/black colornSpecial construction allows ball to maintain balance and keep its shapen6lb, 8lb, 10 lb,12lb,15 lb,18 lb,20 lb, 25 lb, and 30 lb sizesnNot intended for slamming exercises, please refer to j/fit Slam Ball for usenSoft outer core absorbs impact that allows for more explosive solo or partner training. Increase overall strength. Great for beginners and advanced users. The result of using a special combination of cotton, recycled cotton, sand and rubber in the inner core, ensures that the ball keeps its shape and remains balanced and durable.