Shoulder pads are designed to protect the upper body, covering the mid to upper back, shoulders, chest, and upper biceps. They are put on and worn like a shirt. When fitted properly, should fit comfortably with minimal bulk or hindrance to range of motion.
Shoulder pads consist of protective plastic shells at the shoulder caps and other key areas and are lined with multi-density foams that guard from impact. They are usually connected to the body via adjustable Velcro straps.
To properly size, measure the circumference of the player's chest, just below the underarm area. If you have the option of having the player fitted, you want to see the center-line of the player's shoulders, line-up with the center of the shoulder pad caps. This will ensure the shoulder rests properly inside the cap.
Keys to keep in mind when shopping are how bulky the pads are (some caps are bigger than others), the type of protective caps and foams used and the availability of size-adjustment straps, which help the pads fit unique body sizes.