I play with the Prince 03 Tour tennis racquet. Everytime you tension a cross string you have to use the brake on the stringer to keep the string up against the side of the o port. There is an alternative to this however, they make a tool called the Prince Boomerang keychain. I've actually only heard of this tool and seen pictures of it. If anyone else uses this tool please tell me how it works. Also, I can't find any places that sell them so if you know of a place please tell me.