Here's a really cool and rather scarce unlisted porcelain fuse insulator made by Siemens & Sons in Germany circa 1900-1920. This crudely made insulator is marked with their mfr logo underneath the top umbrella, which has a quarter size metal washer embedded in place with a threaded hole. This allows the bottom middle piece which has a machine threaded bolt to attach to the top. The top piece also has a tiny hole that goes all the way through it to allow a low gauge wire to be inserted. This middle piece has two metal pliable clips embedded in the top to allow for a secure fit. On the sides of the middle piece are two clamps and screws for securing the wires. This allows the fuse inside to blow out and shut off power if there is a surge. The middle piece appears to have typical manufacturer made dry process cracking that can be observed in some of the unglazed areas. This middle piece is marked with S313 and S314 above the area where the wires are secured. The bottom skirt has a threaded inner skirt to allow it to be attached to a pin. The bottom piece is slightly warped (and not a perfectly round shape as normally found in German insulators), the base has evidence of hand carving of the extra porcelain (similar to some early US porcelain insulators) and presumably screws into the middle piece as there is a small gap between the two (with no evidence of glaze weld). Has unusually small 1/2" size pinhole.