I'm using the medium tension red, aiming for 2-4 hours per day but in divided sessions. Previously I've always believed the best way to get better at your instrument is just to play it! But after trying to improve my left hand fretting speed for sweeps I finally admitted I'm not the greatest player and I can't sit at work with my guitars! Using this for around a month now I've noticed a massive improvement in my finger control, power and speed. It's great to take to work or just walk around with and get some finger warmups in. My drummer has also used it for stick grip improvements and I think it applies to any musician who uses their hands (that's all of them isn't it? Well maybe not vocalists). Note - the red medium is quite heavy and if you have small or weaker hands, don't jump right in at this level, 7lbs per finger is going to cause cramp or injury if you're not at that level.