Meet the Pronator: a tool you can hold in your hand and get stronger while using it. It improves your shoulder, forearm and wrist strength. You can use any coated dumbbell or resistance band that you can find to use with this system. As you get stronger, you can change the weight easily.
The device is designed to help you build strength in your body and gradually improve your performance. Sets you back $65 at the time of this writing.