To increase power in batting, I've added weight to 3-size softball balls by wrapping them with tape (either masking tape or vinyl tape). They are color-coded: white and yellow. The color coding is for practice purposes, such as hitting with the white balls and practicing taking pitches with the yellow ones. The vinyl tape has been freshly re-wrapped. Recommended for those who want to increase their power and for those who want to practice in a game-like situation using tee-batting. There are 10 yellow balls and 10 white balls.