This is a 1957 Pinco stamped suspension that was cut in half. This shows how the bottom pin is shaped and cemented into the porcelain and how the top cap is cemented on. Notice the rough sand that is probably fired onto the porcelain to give a rough surface for the cement to grab both on the top and inside the pin hole. This one is interesting because if you look closely you can see two small cracks that start near the bottom of the porcelain cap on each side and go up toward the pin at an angle, this insulator may have been damaged from lightning or mechanical stress in use. The small black band on top of the pin appears to be something like pitch or asphalt that was probably added as a cushion for the top of the pin. The shape of the pin is also interesting as most others i have seen have a straight shaft with a simple cone shaped top. the metal is brown from rust because it had been sitting in a damp area before i got the picture. Ignore the brown or black smudges on the porcelain, they are either from the bandsaw blade or just dirt from handling after cutting.