Please, be very, very careful with fingertrainers. In spite of all their focused engineering and admirable originality they may ruin your hands. I have one of these and used it exactly as the photo indicates ... with the pressure coming down on the thumb sideways. The second and third joint on both my thumbs are now ruined and I have not been able to play my guitars for almost two years because of the pain. You'll want the pressure from your finger exercises to come down in your hand or at least at the root of your thumb. DO NOT EMPLOY as shown. The product is certainly OK if used with this reminder. Nothing wrong with that; but you'll want to excert extreme caution with how you are using it. I'm so sad this happened to me and I wouldn't want it happening to any other guitarist.

Bought this so I could maintain my fingertips when on holiday away from guitar. Works a treat, keeps them toughened. The individual finger strength builders are useful in that each can be individually adjusted. Turning them to the stiffest setting provides a challenge. Does what it says it should. Construction seems pretty solid with tough plastic. I suspect it might break if dropped onto a hard surface like floor tiles or concrete so I wouldn't advise that. The rubber grip should last if not abused. I doubt the spring will break.