This is a golf mechanix ferrule trimmer .If you install a new ferrule and find that it is too big for the hosel with an overlap then you can use a device like this to turn it down so that it sits flush with the hosel to give a cleaner look .This is the first time that I have used it so I still need a bit of practice and to get used to it properly by finding the best spot to rest the club and how high to rest the blade etc to get the best results (if anyone that has used something like this wants