Gripmaster GMB

As someone who goes through phases of obsession with legato and Eric Johnson, I have to say that the blue Grip Master is more than enough if this is your first purchase. What truly matters is your grip technique—if you use it like a fitness tool, the product might seem too simple, and you might not be working the correct muscles. I recommend doing a quick search on YouTube after buying it to learn about the proper grip technique. Before I bought it, I thought it would help with my pinky, but surprisingly, my pinky turned out to be stronger than I expected. Interestingly, I noticed significant benefits for my ring finger instead. Slow and steady, and if you keep at it regularly, I'm not sure you'd even need to upgrade to the higher models. My index and middle fingers are already a piece of cake, so if I ever become obsessed with them and want to work them out more, I might consider upgrading to the red one, but I’m not sure I'd even need that.

Qualitywise, it's better than I expected. The springs are thick, and the middle segment feels more durable compared to the plastic on the finger section. If you’re particularly sensitive about plastic materials, you might want to consider the Pro model, but in my opinion, that would be overkill.

I am an intermediate guitarist, and I bought this to help build my hand stamina and strength when away from the guitar. I have downloaded the Gripmaster musicians' workout and tried the exercises. The Gripmaster works as expected, is made of high quality plastics and springs, and the movements are smooth and the strength seems right for me to focus on repetitions. I do not expect miracles, but using this correctly in combination with finger stretches should help build strength and stamina as well as protecting my hands.
###UPDATE###
After about a month of following Prohands' musicians' program, a complete stretching routine and regular guitar practice, there is a notable (but not miraculous) improvement in endurance and strength, better hammer-ons and bends, and significantly less cramping, and not just with the guitar. I will happily continue this regimen daily. I have purposely avoided made-up exercises and overuse. Consistency is key.