A really good finger exerciser. Good build quality. Being able to adjust the pressure of the plungers is excellent.
You can hold it in your hand or ,as I do, just put the thumb on the base to strengthen your thumb muscles as well.
I have just started to learn the guitar and have used it for about 5 minutes a time several times a day for the last two weeks and there is a definite improvement in my finger strength. It really improved the strength of my little finger as well which previously had hardly any strength in it at all.
I highly recommend this product to anyone who wants to improve their finger strength.