Catcher"s Thumb Guard disperses impact to help protect thumb from injury or hyper-extension (including Gamekeeper"s Thumb); Perfect for both elite catchers catching 90+ MPH and youth catchers new to the position * Straight from the Pros; Official MLB Authentic On-Field Collection gear worn by all 30 MLB organizations & Elite Collegiate programs * Custom-molding technology air activates in minutes for a true custom fit to your thumb; Easy fitting process- no cutting, boiling or baking required * ¼" thin Shield custom-molds inside your glove for ultimate comfort and support that won"t interfere with your game * Multi-sport use for lacrosse, football, skiing and more; Coverage Area: Large: 4.5" x 4.5"; Small/Youth: 4.25" x 3.25"