Self ballasted Mercury vapour bulb

Today i want to show you a rare bulb. Its a 160W self ballasted mercury bulb. This means it does not require an aditional ballast ore starter. The ballasting is doen using a tungsten fillament to limit the current. It also means that the life of the bulb is only around 6.000 h and its energy efficency class C. Despike of that its a very cool bulb and rare !