The D10 has a fairly simple design overall. The head houses a dual coated impact resistant glass lens up the front which provides an improved light transmission out from the LED. Behind the lens sits a textured reflector. As you can see from the image to the right, the reflector and LED are well-aligned and does a great job of focusing the light. On its exterior, the entire head is coated in a very dark gray Type 3 anodized coating providing added durability. This anodizing is very nicely done, consistent and free of any smudges or scratches. Diamond-textured knurling covers almost the entire outer surface of the head. This knurling is nice and rough which provides very good grip, just like all the other NiteCore products. Viewed from the rear end we can see the part of the electronic's PCB and also the switching mechanism of the Smart PD (piston drive) system which is a spring-mounted ring acting as a switch instead of the common push button switch modules housed at the rear end. Threads in the head are nicely cut and are anodized as well.

The body is made up of just the battery tube with no separate tail cap. Inside the battery tube is a additional metal tube in which the battery sits. This tube acts like a piston. It simply slots into the battery tube with its rear sticking out the tail end of the battery tube. A red rubber o-ring sits towards the rear end of this piston which provides resistance to the piston mechanism as well as water resistance. The D10 has an IPX-8 rating, to the depth of which stated by the manufacturer. Incidentally, I could not find any stated depth rating on the NiteCore web site. The interior of the tube has a spring on at the "-" end for the battery contact which ensure there will be no battery rattle, and is also nickel coated which gives it a nicer looking finish. This is a unique switching mechanism for a flashlight which is supposed to provide improved power transmission and durability. However there was one thing I didn't like about it. I find that it provides very poor tactile feedback when depressing the switch. Adding to this, the switch also has short travel. Both these issues results in the poor tactile feedback of the switching mechanism. Thankfully, the Smart PD system also allows the light to be activated via twist action, however by using this twist switch mechanism, you loose the ability to switch or select output levels. The threads on the battery tube is just as nicely cut as those on the head and fit very smoothly together with no grinding or cross-threading. A rubber o-ring sits just below the threads on the tail cap which provides resistance for the twist switch action and also waterproofing. Type 3 anodizing throughout the battery tube is consistent and smooth, the dark gray color matches that on the head very well. Almost the entire outer surface of the battery tube is covered in diamond-textured knurling matching that of the head as well giving the D10 an overall consistent design. Right at the end are are holes which allows for lanyard and key chain attachments. The switch sits slightly recessed thus allowing the light to tail stand on flat surfaces without problem.

If you're unfamiliar with any of the terms used in this review, click here for explanations on common flashlight related vocabulary.

The D10 is capable of 3 levels of output, a fixed 1% (3-5 lumens) and 100% (130 lumens), and a customizable level. The custom level is what I would call a temporary setting as it will be lost once you switch to either the preset 1% or 100% level. Operating modes has been very well described and explained in the following video.

The beam profile from my sample provides a medium sized hotspot which has a slight dark circle around it. Overall beam color is very close to perfect white, leaning slightly to the cool side. The spill beam provided provides adequate illumination for peripheral vision. Regulation is well-maintained on an AA cell, but diminishes gradually to about 75% before stabilizing when running on 3.7V 14500 cells.

The Good - Machining, fit and finish is excellent. Simple and practical body design. Simple interface for custom brightness setting. Smooth ramping of brightness level. Good output intensity.

The Bad - Poor tactile feedback and short travel from the piston drive switching mechanism. Below average runtime on AA cells.

The Relative - Almost perfectly white tint, leaning slightly to the cool side. Is able to function as both a push button with momentary function, and twist activated switching mechanism. Is able to tail stand.

Head (front view).

Head (side view).

Head (rear view).

Piston drive tube (front view).

Piston drive tube (side view).

Piston drive tube (rear view).

Battery tube (front view).

Battery tube (side view).

Battery tube (rear view).