I have two vices in my carpentry shop, both with metal jaws. This set of rubber and magnetic nocks pairs well with existing nock surfaces. The magnet is strong and sticks well to the face. The rubber surface cushions the gripping side of the jaw, minimizing damage that can occur when using a vise to hold objects. I mainly work with wood, which can be damaged with jaws in a vise. With these blocks I can hold objects stable without damaging the work piece. I think this is a great addition to your metal vise jaws.