The newest development in light sources are white LEDs. A LED or Light Emitting Diode is a rather simple semiconductor circuit which emits light without producing waste heat. This means, it needs only very little energy, about 5% of a incandescent light bulb to produce the same amount of light. They are known for a long time but always produced coloured light, when the while LED was developed in the 1990s the were first used for bicycles and for handheld lamps.
Cavers were among the first to adapt this new technology for their lamps. The reasons are simple, a result of the advantages and disadvantages of the new technology. In the early years LEDs were not very bright, but cavers were able to handle this. Cavers stay for hours in the caves and the eyes have time to adapt to the low light. The electric lamps with traditional incandescent bulbs were also not very bright, but needed a lot of energy. But the problem were the batteries, for longer expeditions a lot of batteries were needed, which was both expensive and heavy. And rechargeable batteries were not helpful if you were not able to recharge them daily, which is impossible on a cave expedition. So this lamps became rather common among cavers quite early.
Mainstream has since those early years adopted, all handheld lamps which are now sold are based on LEDs. The LED has become quite cheap and and much brighter, modern lamps contain a single LED, where some years ago an array of a dozen was needed. And while there is an abundance of cheap models from China, cavers still user their own models. Because they are built for the tough and wet environment and are optimized for use as a headlamp.