If so, the fusible element is the fuse link 'wire' that need to be replaced after a fuse operation. They are usually ship in plastic bags with ratings stated. Manufacturers place cryptic markings on them for themselves to denote the ratings --- not all that useful to users.
If you need to replace the fuse link without any previous records, and you could not find the original manufacturer, your best bet would be to approach it from the application, such as size of transformer to protect, etc.
Horn Gap fuses are open wired fuses where fuse is linked between two live rods, which are shaped like bull's horn (sort of V shaped). This gap is provided to blow out the fuse outwards in the event of a fault.