Maybe I did it a bit exaggerated with the medium version (red), because pressing 7.5 pounds with individual fingers is pretty heavy. Nevertheless, I am very satisfied! Shown are the first successes, my finger strength has definitely improved. Because the surfaces while ensuring through tiny relief-like right corner of the grip on the handle surface is provided for good finger grip, while at the same callus formation is unavoidable (unless you look Cotton gloves attracts)
The Quality? The can be proud of! A very stable device, the springs squeak and not creak. The hard plastic is very good, very robust process and throughout the device is also very handy.
For people with weak fingers, I recommend a maximum of the blue Gripmaster (light), for the "medium" is required before striking force of a craftsman.
Conclusion: I fully buy recommendation!