Door-shaped Electron Beam Tungsten Filament with Two Hooks

Door shaped electron beam tungsten filament is with the shape like a door. There are two legs for this kind of electron beam tungsten filament.
The regular diameter is 0.55mm and 0.8mm.
As for its two hooks, they are shaped at the end of the leg, and has been popular dwg. for door shaped electron beam tungsten filament.