The Custom Shoulder Rest XL. Getting comfortable with your violin is important for successful practice and performance. The instrument is cradled intimately against the body, yet all players are shaped differently. The Custom Shoulder Rest XL for the NS Violin can be formed by the player to fit his or her body perfectly. Firm foam is backed by a layer of malleable aluminum that can be bent with thumb and forefingers to mold the rest into virtually any position. Once the shoulder rest is formed, the shape remains fixed, providing a secure structural platform.