ShoulderHorn, Size 2, Medium/Large, Rotator Cuff Training Device SIZE 2, Medium/Large, is for people who stand up to 6' tall and weigh up to 200 lbs Locks your shoulder and arms to train/rehabilitate the shoulder in an "abducted external rotation" which trains your shoulders to work against great loads like lifting, throwing, and other overhead motions common in many sports. Designed so the weight of the upper arm is supported in the correct position, which isolates and strengthens primarily the muscles of rotator cuff, which is critical to strength and rehabilitation of the shoulder. Constructed of a single length of formed steel tubing, and is covered in dense foam padding making it extremely strong but VERY LIGHT IN WEIGHT (under 3 lbs). University study showed the ShoulderHorn was MORE EFFECTIVE for increasing external rotator strength than using dumbbells alone. ("Effects of the Shoulder horn and Lightweight Dumbbell Training on Shoulder External Rotators," published by Journal of Physcial Therapy Science.)