When do you need which mitt? - Catching glove left = throwing hand right - Catching glove right = throwing hand left. What is the catcher's mitt used for? Every player on the field team wears a baseball glove to pick up or catch the ball, which enables the ball to be caught easily and painlessly. Which size is recommended for which age group? Children and young people up to 11 years = Junior catching glove. Teenagers aged 12 and over and adults = Senior catching glove.