Dubs Machine Training Balls are built out of high density foam to work in pitching machines for hitters and catchers. Since these balls are made to be 3oz., they provide an excellent feel off the bat, even at higher velocity, while giving great feedback to hitters. The foam material extends the life of bats in batting cages and saves hitters' hands with repeated swings. Sometimes you just want to take a lot of swings and work out some things in the cage, and with these balls you can hit for longer without getting tired or stinging hands. For catchers, these ball are great for blocking drills to get proper footwork and body positions without fear of getting hurt while learning to block, one knee down blocking drills, or with competitive athletic blocking drills and games.