Overview & First Impressions
Cave survey is part mapping, part geology and part stubbornness. Teams measure passages, sketch cross sections, photograph formations and sample mineral traces, often several hours from daylight in air that is wet and close to freezing. Lighting is not one problem but three: you need a dependable main beam, a backup that lives on your helmet, and a UV source that reveals what white light hides. Klarus flashlights cover the third job neatly with a dual-emitter design.
Materials & Construction
The RS20UV puts a UV emitter alongside a conventional white beam in one sealed housing, so a surveyor does not have to carry two separate lamps into a passage. Machined aluminium and an anodised finish survive being dragged against rock, and the switch is recessed to prevent accidental activation inside a pack. A rechargeable cell keeps consumable waste out of the cave, which is both an environmental point and a practical one.
Design & Details
The UV output is the specialist feature: it makes fluorescent minerals glow, shows up calcite deposition patterns and exposes biological traces that are invisible under a normal torch. Eyewear matters, so a lens rated for UV blocks the scatter that would otherwise make the room uncomfortable. The white beam uses a conventional reflector for a clean hotspot. Anyone who already carries EDC knives and a primary light understands the logic: one tool, two functions, less weight in the pack.
Real-World Use
A survey push means crawling, stooping, measuring and sketching for hours, with the main lamp on the helmet and the UV torch in a chest pocket for spot checks. Between passes, the team checks samples, marks stations with tape and photographs a formation that will be flooded next season. The UV beam turns an ordinary wall into a record of mineral deposition, which is exactly the sort of detail that makes a written survey worth publishing rather than simply finishing.
Ownership Notes
Rules in caves are strict, and gear choice should respect them. Never leave spent cells or debris underground, and never expose another team member's eyes to UV. Clean the lens with a soft cloth because cave grit is abrasive, dry the housing before sealing it in a dry bag, and check the switch boot for cracks after every trip. A small folder in a pack pocket is standard survey kit for cutting tape and cord, which is why folding knives with a serviceable pivot stay in every caver's kit, and EdcMall stocks both the lamps and the tape carriers that go with them. The same rule holds underground: an EDC flashlight in a chest pocket backs up the helmet lamp, and a survey team carrying two lights is a survey team that finishes the passage instead of turning back early.
Who Is This For?
This suits cavers, cave surveyors, geologists and mineral collectors who work underground. It also suits anyone documenting fluorescent specimens at home, since the same lamp works on a benchtop. If you only visit show caves with fixed lighting, you do not need UV capability. Buy the RS20UV when your survey needs one lamp that answers both a white-light and a fluorescence question in the same passage.
Final Verdict
A UV torch is one of those tools that looks like a novelty until the first time it reveals calcite banding on a wall you had already walked past twice. Paired with a solid white beam, a sealed body and a rechargeable cell, the RS20UV earns its weight in a survey pack. Cave work punishes gear that fails quietly, and this lamp does not fail quietly.
