Thera-Band® Hand Exerciser 
Thera-Band® Hand Exercisers are specially formulated exercisers provided in a progressive sequence of four translucent colors. They’re used for hand, finger and forearm strengthening, as well as hot and cold therapy. The softer yellow and red models fill the gap between putty and spring devices and they’re not as messy as putty. Progressive resistance in different levels of compression allow each exercise to be geared to the patient and they show a clear measure of progress. Place a Hand Exerciser into the microwave or freezer for hot or cold use.
This translucent and cushiony ball will give your fingers, hands, and forearms a workout.
If you are looking for a hand-exerciser of moderate difficulty – somewhere between therapy putty and spring hand exercise devices – you need look no further than this easily compressed, soft ball.
TheraBand offers a selection of hand exercisers in progressive resistances. Pick the one most suited to your current hand strength and fitness. Then, as your fingers, hands, and forearms strengthen, switch to a ball that is harder to compress. 
The balls follow the familiar TheraBand sequence beginning with yellow (extra soft), then moving to red (soft). Following red come green (medium) and blue (firm).
Use your hand exerciser to strengthen your grip, improve coordination and hand motion, even exercise your thumbs. Pop it in the freezer for cold therapy, or in the microwave (heat in 5 second increments to a maximum of 20 seconds) for hot therapy. Works great as a stress-reliever too!
Some hand exercise balls have a tacky feel, but not this one.
2″ diameter soft 3# red ball comes with an illustrated instructional manual.
BLACK x-firm
This is the ultimate TheraBand hand exerciser, designed for those already having a high level of hand fitness.
Manipulating this extra firm, translucent ball will give your fingers, hands, and forearms a solid workout. Work on honing your grip, building dexterity, improving coordination and hand motion.