Remember the days of filament bulbs in head torches? Lots of batteries and spare bulbs that always seemed to be broken by the time you needed them?
Modern torches use Light Emitting Diodes (for the nerds) instead. LEDs have been around since the 60's but although those used in todays torches may look the same the technology and manufacturing processes are vastly different. Modern LEDs now emit enough light to navigate and work by while still consuming a fraction of the power that a traditional filament bulb does. As they are solid state they are much less likely to break and as most torches have multiple LEDs you aren't going to be left in the dark very often.
There are many brands of head torches on the market but Petzl are hard to beat. Ideal for tactical military use with features like red filters, multiple light levels and flashing modes for signalling they should be one of the first things to go in your Bergan.