One size, adjustable. Thumb loop holds hand in ideal position.The ACE Brand Arm Sling lends a helping hand by keeping your arm in the optimal position. An adjustable, padded shoulder strap provides a comfortable, personalized fit, while a thumbhole loop holds your hand in place. Featuring a convenient buckle at the strap that’s easily manageable with one hand, the ACE Brand Arm Sling lets you comfortably go about your day to day on the road to 100%.