The Fenix HP10 and HL20 proved that the company could make some awesome headlamps. The HP20 took the company to a whole new level, proving that they could make a top notch headlamp with few equals. The HP20 is made for rough use, with cavers and other people that are notoriously rough on their gear in mind.
The HP20 has several interesting features. One is the fact that the battery pack is not meant to be worn on the head, but instead comes with a removable clip holder that can be attached to your belt, pack, or anywhere else. The light has two switch systems, one on the battery pack and another in the middle of the wire running between the lighting unit and the battery pack. The battery pack one is like a kill switch, where turning it off will mean that the light cannot turn on. The other switch system has two switches that are always illuminated by LEDs, making finding them in the dark easy. One of these switches will switch mode groups and put the light in standby, turning it off until you want to use it again. The second switch will switch between the modes in each group, four outputs and some flashing modes.
The reflector and head are relatively large on the HP20, meaning that the throw is a lot better than your average headlamp. It uses one of the latest and greatest CREE XP-G LEDs for around 230 lumens on high. Here is a video that shows it in action: