The original jaws of a vise are precision machined parts in a particularly resistant metal and are expensive to replace (on Facom type of vices, Dolex, Sambre-Meuse, ...) These aluminum jaws Draper have not really meant to protect the original bits, but rather to protect the piece to tighten. A therefore recommended for sensitive parts, rubber surface crushing slightly to fit the shape of the part and producing a controlled tightening. However it is true that the magnets are a little weak, but it is not fatal to use.
