Each of Bob's guitars incorporates his personal design, hand-built hard tail bridge, which is copper and nickel plated, over the cold-rolled steel that he uses to fabricate them. If you compare this design to a "regular" off the shelf hard tail bridge, you MIGHT notice some differences! Bob doesn't like brass, copper or aluminum, since he considers them to be inferior as to the tone that is imparted by these commonly-used metals... so he goes to quite a bit of trouble to build his own. Kind of par for the course, as they say. They go with his custom ferrules. We will head to the plater down in the valley in a few weeks when everything is ready to go!