If you have never used these I woud start with the smaller ones first so your hand and fingers get use to it. Cause they do tend to get soar. If you start with the thicker ones you may not be able to complete the exercise. I got the 2.5 and 3 to start me off. 2.5 has really created more finger muscle fibers cause I feel my grip strength much more stronger. I can hold on to barbels and any rods much more longer when not using these grips strength enhancers. I feel like my hand shake is much more solid. Handshake, because I do a few business meetings and I shake hands a lot.

I can deadlift 400lbs without straps, and I lift with a 2.25" axle all the time, but the real test of finger strength is just opening these darn things up to put onto a bar or dumbbells. I like these grips, I just wish the rubber was a little less firm so I didn't have to kill myself putting them on/taking them off every time I want to use them.