Never throw it full speed! My students love this 1-pound solid rubber ball! Note that it's similar in size to an 11" ball. It's great for warming up, arm strengthening and shoulder rehab.Throw overhand slowly 10-15 times. This heavy, solid rubber training ball is too heavy to do the windmill motion at full speed so do lots of snapping drills: sit & snap as high as you can from under your leg, sideways snaps, line drive flicks, pendulum snaps, slow windmills. Cannonballs are great for curve, rise and drop ball spins.