The head of the I10 houses a unique reflector cup which is half smooth and half textured, similar to earlier Olight models. The smooth surface area reflects a highly focused hot spot for optimal throw, while the textured surface area smoothens out any artifacts in the spill region of the beam profile. Its an innovative take on reflector design and produces a beam that is characteristic of Olight products. The emitter is just slightly off-center, but not by much. On the exterior, the head has a thin band of checkered knurling which provides some grip when you're twisting the head. The Type 3 hard anodized coating is smooth and consistent throughout, free of scratches or smudges. The threads on the head are not too thin or too thick. New to the I-series is an anti-roll feature in the form of a 6-sided hex shaped ring towards the rear end of the hear.

The battery tube has a simple and clean looking design. There're four flat faces machined onto the tube. The battery tube can accommodate protected 16340 cells just fine. As with the head, coating on the battery tube is just as well done. Very smooth and consistent. The threads between the battery tube and the tail cap are cut very smooth. I noticed that the more force you apply while screwing on the tail cap, the higher the chances of it getting cross-threaded. Otherwise, it screws on perfectly fine and smooth. The tail has a band of checkered textured knurling similar to that on its head. This provides adequate grip when unscrewing for battery changes. Housed inside the tail cap is a forward push button switch module. The clicking mechanism is on the stiff side with average travel and produces a positive clicking sound when engaged. The I10 can't tail stand since the rubber switch cap slightly sticks out the rear end of the tail end. The I10 is rated at IP-68 for water and dust resistance.

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Instead of having pre-defined brightness levels, the Olight I-series uses twists of the head to smoothly ramp its brightness level up or down. The direction of ramping alternates each time you loosen the head. To set the brightness level, simply tighten the head when you reach a particular brightness level during the ramping sequence. The I10 uses R2-binned LED's providing an output range of 6 to 205 lumens, taking about 2.5 seconds for a full ramp sequence either way. The digital current regulated circuit provides constant light output on all brightness levels with no signs of PWM flickering. You can also activate strobe and S.O.S. modes by half-pressing the switch within 2 seconds each time.

The color temperature on my sample is a neutral white, just slightly cool when compared to sunlight white. The beam profile has a spot which is well-focused and the spill beam is smooth without artifact thanks to its unique reflector design. There is a slight dark area right in the middle of the hotspot, but its not noticeable in practical use. The I10 shares what looks like an identical circuit to that of the limited edition Olight Titanium Infinitum which provides improved performance over the T-series.

Runtime is good for the intensity of light it outputs on the brightest level. Regulation is also maintained well on either CR123 or 16340 cells.

The Good - Very well built and finished. Provides a well-focused spot while still having a smooth, artifact-free spill beam. Maintains regulation nicely with 3.0V CR123 or 3.7V 16340 cell while providing good output and runtime even on the brightest level.

The Bad - Slightly longer than most single CR123 powered lights.

The Relative - Half textured and half smoothened reflector provides a unique beam profile which has a highly focused spot. Beam has a neutral white color temperature. Uses a forward push button. Is unable to 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).