The suction cup on the base of an arm prosthesis can be used to attach the device directly to your skin. This provides a more secure connection than relying on a strap or harness, and it also helps to distribute the weight of the arm more evenly across your body. The grip on the arm of the prosthesis can be used to hold and manipulate objects, just like a natural hand. There are a variety of different grips that can be used depending on what you need to do with the arm.