The Neoprene Shoulder Brace has two adjustable upper arm cuffs fix with hook/loop at the back of the neck, to prevent shoulder subluxation and hold the head of humerus in the glenoid cavity. 

To size measure- Mid Upper Arm Circumference: 

S 23 - 28 cm

M 28-33cm 

L 33-38cm 

XL 38-43cm