The entire head of the TK12 is machine from aluminum with a 5-point crenellated bezel which allows you to see if the light has been left on when placed head down. The bezel is thick and seems tough enough to stand up against daily usage. Beneath the bezel sits a toughened, AR coated glass lens similar to other Fenix products. A very lightly textured reflector is used in the TK12. Surface finishing on the reflector seems to be very well done indeed, highly polished and consistent. The emitter and reflector are perfectly aligned in my sample. The exterior sides of the head has 6 shallow scallops machined on it which seems to be more of an aesthetic touch, they don't really work well as an anti-roll feature. Looking inside the rear end of the head you'll see the PCB for the "+" battery contact though do take note that the TK12 does not have the reverse polarity protection implemented so that it will work with flat-topped 18650 cells. The threads on the head are smooth, clean and thick.

The battery tube maintains a fairly clean look, with a thing raised lip machined at the front of the battery tube. There's a band of diamond textured knurling about 3cm wide, and two flat surfaces machined on with the Fenix branding printed on it. The TK12 has great ergonomics, it feels really comfortable and secure in hand with a hefty mass. I did find the grip ring to be slightly uncomfortable when holding the TK12 in an overhand grip, and it's also a little small for comfortably holding in a cigar-style grip, very much like that of the TK11. The wall of the battery tube is very thick, I'm confident that it can handle rugged abuse. Its internal diameter is wide enough to accommodate protected 17670 cells. If you wish to use 18650 cells, you will need to purchase the 18650 separately. The wall of the 18650 tube is obviously slightly thinner since it has a wider inner diameter. Threads on either ends of the battery tube are very well done, smooth and thick. Head and tail cap screw on very easily without any cross-threading or grinding, very nice. There are thick rubber o-rings which came generously lubricated. These serve are water seals, 2 at the front end and 1 at the rear end. The TK12 is advertised as meeting IPX-8 waterproof standards, although maximum submersion depth wasn't specified by the manufacturer. The threads at the rear end is coated as well so the light can be locked-out by loosening the tail cap. Type 3 anodized coating on its exterior surface is smooth and consistent throughout.

The tail cap has a hand of knurling for grip. At the rear end the tail cap has a deep 4-point scallop machined into it, one of the points has a hole for lanyard or key ring attachments. The rubber switch cap has a checkered texture and feels quite thick, and also protrudes out slightly from the tail cap so tail standing is impossible. The switch module housed in the tail cap is a forward push button, allowing for momentary activation which I personally think is a must-have for tactical flashlights. The switch has a noticeably longer travel than other Fenix products which use reverse push buttons. Clicking on the switch provides good tactile feedback and audible click. Switching mechanism is responsive so signaling with the TK12 poses no problems.

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

The user interface of the TK12 is a welcomed progression from that of the earlier Fenix T-series. It provides three levels of constant output and a strobe mode. These are broken down to three sets with two output modes each as described below. Do take note that the lumen values below are manufacturer rated, actual measured lumen values can be found in the column to the right.

Outdoor mode: Output A/50 lumens, Output B/225 lumens.
Camping mode: Output A/5 lumens, Output B/90 lumens.
Hunting mode: Output A/Strobe, Output B/225 lumens.

Output A is when the head is loosened, and B is when tightened. Cycling between Outdoor, Camping and Hunting modes is done by loosening and tightening the head twice (i.e. A > B > A > B) quickly within 0.5 seconds. There is a slight correction to the manual though, as during tests I found the order of modes to be Camping, Outdoor, then Hunting instead. The beam profile from the TK12 produces a well-defined medium sized hotspot with slightly soft edge, and no discernable corona tapering off towards the spill beam. There're minimal beam artifacts aside from the common dark ring around the hotspot, as with most XR-E based lights. Beam tint on my review sample was very close to sunlight white.

Runtime performance is above average, as can be seen from the graphs below. This is the first product by Fenix which seems to have electronics designed to properly handle input power from a single 3.7V 18650 cell. Regulation is also maintained well for most of the battery life with all battery configurations, then gradually tapers off towards the end. By the way for those wondering, the runtime results for the 50 lumen level is indeed correct. Both battery configurations hit the 50% mark at the same minute.

The Good - Solid build quality and cleanly machined. Nicely designed anti-roll grip ring which work well. Tactile and responsive switch.

The Bad - Grip ring is uncomfortable when held in an overhand grip and is slightly too small to hold securely in a cigar-style grip.

The Relative - Neutral white beam tint, close to sunlight white. Uses a forward push button which allows for momentary activation. Can't tail stand.

Head (front view).

Head (side view).

Head (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).