They are 45mm silver balls that develop different rainbow patterns on them from hand oil. There is a little mellow bell inside both spheres which vibrates when they hit each other. After a couple of hours of pacing around the carpet, I was able to keep them in one hand for about 30 minutes at a stretch without dropping one. It made the drive time pass rather quickly. I enjoyed choosing different hand exercisers to use in my palm.
Variety is the spice of life and probably the way to healthy hands.
It was first published in 1988 and is filled with hand and finger drills illustrated through black and white photos. It is the only hand exerciser supported by the Windows RSI software application, EgroSentry. EgroSentry functions behind the scenes monitoring computer usage patterns while using an application, like the number of keystrokes over time, alerting you with a tone or drop down menu box when it is time to take a break. Occupational therapists remommend that regular micro breaks are the single most important activity that can reduce the risk of getting repetitive strain injuries. If you use a hand or wrist exercise product, I would like to hear about your experience.