The head houses an XR-E emitter and focused by a smooth aluminum reflector. Emitter and reflector are alligned very well, perhaps leaning just a hair to one side but really it's almost perfect. The reflector rests on the silver ring of the XR-E instead of around it on its PCB. The lens used is made or hardened AR coated glass for increased light transmition as compared to regular uncoated glass. The Type 3 coating is a little smooth for my taste, which coupled with it's short battery tube, sometimes makes it slightly difficult to twist for single handed changing of operating modes. The emitter module is sealed inside the head and is not easily disassembled.

They body of the L1D CE is similar in size to most single AA cell lights such as the LumaPower LM301, but slightly larger than the twist activated C-LE. These kinds of AA lights are a little big to carry on your key chain. If you are used to carrying lights in holsters, the L1D will be perfect on your belt. The entire light is coated in Type 3 anodizing. One thing to note is that the coating on the current line of Fenix lights is smoother and more shiny compared to the earlier LxP series of lights. The body still has a hexagonal shaped tube, the head is smooth with a couple of ring designs around it. The aluminum body of the L1D is very thick and sturdy, similar to the LM301. Inside the body is all nice and cleanly finished, at the head end you will find the PCB for the "+" contact. The threads on this light are almost perfect. They are very smooth and free from accidental cross-threading, you won't need to turn them counter-clockwise to get the threads to align. Throughout the entire testing phase of this light, I did not experience any sign of cross-threading.

The tail cap houses a reverse push button. The rubber cap over the switch is smooth and doesn't have any texture on it. I really like the response of the switch, it's not too soft or too stiff and it has really short travel. This could be a bad characteristic if your carry this light in your pocket though since the switch is much easier to turn on. There's a thin band of checked texture around the tail cap which helps a little when unscrewing the tail cap. The "-" contact spring is gold plated and all the rubber o-ring came very well lubricated. Lastly, there are two holes and a notch for attaching straps or key ring while still allowing the light to tail stand.

The L1D CE has 6 modes in total, separated into 2 sets according to the position of the bezel. Cycling through modes in either set is done by half-pressing the push button, sort of like how the auto focus works on a digital camera.

Set 1 (loosened bezel)
Off > Low > Medium > High > S.O.S.

Set 2 (tightened bezel)
Off > Turbo > Strobe

All the different levels on the L1D CE are controlled true constant current regulation. This means that you will not experience any high frequency pulsing, unlike the C-LE for example which uses PWM to achieve lower output levels. One thing which I've never figured out about Fenix lights is why they don't have better tint considering their price point. Even since their earlier P1 and LxP models which had varying tints of yellow, green and blue. My L1D CE sample has a warm yellow tint, while other lights such as the JETBeam C-LE and even the MXDL-style Cree both have almost perfectly white tint. The dark ring around the hotspot is present as well, just like is most other XR-E based lights.

Overall output is very good, on High mode it's really impressive considering it's only running on a single AA cell. Runtime is also very good, the regulation circuit works very well. Only bad thing about the L1D is that there really isn't much difference in output between High and Turbo modes. In my opinion Fenix should have advertised the L1D as a 5-mode light since the turbo mode is only effectively achieved on the 2x AA version of the light. They use the exact same head module for both the L1D and L2D models, without considering the different input voltages from single and 2x AA cells. This gave me the impression that Fenix designed the circuit primarily for a 2x AA setup, and made a single AA body version just for the sake of it.

Runtime 1x AA 2000mAh Eneloop Low 24+ hours Medium 4:26 to 50% High 1:36 to 50% Turbo 1:37 to 50%

The Good - Very good output on High mode, great build quality as expected by Fenix. Type 3 anodizing, perfectly smooth and aligned threads, well engineered smooth aluminum reflector and AR coated toughened glass lens. True constant current regulated output levels.

The Bad - Price is a little high compared to other production brands currently on the market. Practically, there isn't a Turbo mode.

The Relative - The dark ring which is commonly associated with XR-E lights it present in the L1D CE as well, but only appears within about a meter. It really doesn't affect practical usage at all. The reverse push button, some people like it because it reduces the chance of accidental turn on while stored in pockets or bags, others hate it because it doesn't allow momentary on functionality. Lastly, tint is not as good as it can be, even the $9.99 MXDL-style Cree has a much whiter tint. While the tint doesn't affect performance and usability, I would have expected a better tint control for the price. However, the tint may also be a result of variations even within the same emitter bins, just like the Luxeon lottery. Perhaps I just got unlucky with this particular sample.

Head module (front view).

Head module (side view).

Head module (rear view).

Battery tube (front view).

Battery tube (side view).

Battery tube (rear view).

Tail cap (front view).

Tail cap (side view).

Tail cap (rear view).