Catcher's gloves are measured by their circumference, whereas all other mitts are measured by length. A catcher's glove is typically 31 to 33 inches. The reason for this is simple: the catcher's mitt is a target for pitchers, who try to throw the ball wherever the catcher sets up the mitt. Catcher's gloves are also heavily padded, especially on the thumb and palm area, since catchers experience the most "sting" from fast balls.
With conjoined, mitten-like fingers, closed web patterns, and extra padding on the top and bottom, catcher's gloves are designed to trap balls. The catcher's main objective is to receive pitches, and sometimes to hang on to foul tips, therefore trapping the ball in the glove is paramount.
From brands like Mizuno, Wilson, Rawlings, Marucci, All-Star, Under Armour, Nokona, Louisville Slugger, Easton, and Adidas, it's easy to find the right catcher's glove. Always try a glove on before buying it to ensure the fit is good and it won't slide off your hand. And, of course, you always want to use it in practice or play catch with it to break it in before using it in a game for the first time.