The Anduril UI, explained

Anduril is open-source flashlight firmware. It exists because enthusiast users wanted control that mainstream interfaces do not offer, and it delivers that at the cost of being genuinely hard to learn.

This page is a map rather than a manual. Every light using Anduril ships with its own documentation and the details vary by version and by model; what follows is the structure, so the documentation makes sense when you read it.

What it actually gives you

• Stepless ramping. Hold the button and the output rises smoothly rather than jumping between fixed levels. Release where you want it.
• A configurable ramp. You set the floor and the ceiling, so the light never goes brighter or dimmer than you want it to.
• A moonlight mode measured in fractions of a lumen. Genuinely useful at night and something almost no mainstream light offers.
• Thermal configuration. You set the temperature at which the light steps down.
• Battery voltage readout, blinked out by the emitter.
• A set of blinky modes — beacon, candle, lightning, party strobe — that are mostly novelties and one of which you will use.

Simple and advanced

Anduril 2 introduced two modes, and this is the single most useful thing to know about it.

If you have bought an Anduril light and found it baffling, switching it to Simple UI is usually the right move. You keep the excellent moonlight mode and the smooth ramp and lose the parts you were not going to use.

The click language

Anduril's notation writes a sequence as clicks followed by an optional hold. 3C is three clicks. 2H is click twice and hold the second press. Once you can read that, the official diagrams become usable.

That table is a starting point rather than a specification. Sequences differ between Anduril versions and between models, and your light's own documentation is authoritative.

Lockout is the one to learn first

Four clicks locks the light. In lockout, a click gives momentary moonlight — which is genuinely useful, because you get a tiny amount of light without unlocking anything. Four clicks again unlocks it.

On a light capable of thousands of lumens sitting in a pocket, this matters. An accidental turbo activation in a bag gets hot enough to be a hazard and will flatten the cell.

Configuring the ramp

The most valuable single configuration is setting the ramp ceiling below turbo. Most people rarely want maximum output, and capping the ramp means the ordinary hold-to-brighten gesture never overshoots into a level that overheats the light.

The second most valuable is setting the thermal limit sensibly. Too high and the light gets uncomfortable to hold; too low and it steps down before it needed to.

Should you buy an Anduril light

If you enjoy configuring things, it is the best interface available and nothing mainstream comes close. If you want a light that works when you pick it up, a two-mode SureFire or a programmable Streamlight will make you happier.

There is also a practical consideration: Anduril lights come mostly from small enthusiast manufacturers, which affects availability, warranty and support. What to look for in a flashlight covers the mainstream alternatives.