The Metolius GripSaver Plus was designed with the help of a doctor to strengthen and balance the muscles of the hand, wrist and forearm. It's super-effective for rehab or prevention of climbing-related finger, wrist and elbow injuries. 
It extensively exercises the hand through a full, natural range of motions. The GripSaver plus is an essential tool for serious climbers. Including step-by-step instructions. 
3 firmnesses available: Soft (blue), Regular (red) and Hard (orange)