The head of the Streamlight Microstream houses a 0.5 watt white emitter which is similar to those used in some of the other recent line of Streamlight products. The product specifications does not indicate exactly the model or brand of emitter the Microstream uses. Judging from the beam profile and tint, it does seem similar to Nichia emitters. The lens used is made of polycarbonate and is advertised as scratch resistant. Output light is focused by a smooth reflector which is slightly off-center in my sample. This doesn't really affect the beam profile though. The entire head is sealed to the battery tube with epoxy adhesive. There're bands of rings machined half way down the exterior of the head, purely a cosmetic touch. Anodized coating has a matte finish, its smooth and consistent.

As mentioned above, the battery tube and head are sealed together. The head is actually slightly longer than the battery tube itself. Design of the battery tube is a plain cylinder with no flat sides or other machining touches. This simple design keeps the battery tube as slim as possible which is nice. The Streamlight branding is printed on the battery tube as well. Coating is well done and consistent on the battery tube as well. The tail cap houses a forward push button switch, which means that its capable of momentary activation. The button has average tension, and momentary activation is easy. Clicking provides a tactile feedback, however this switch has fairly long travel. Paired with the fact that the button is quite tiny makes it difficult to click on, especially if you have large thumbs. You'll probably need to use the tip of your thumb or fingernail. The threads are well cut, but comes dry from the factory which might make them feel a little rough. Applying some lubricant on the threads is recommended. The Microstream also comes with a metal clip which snaps onto the tail cap. There is a design flaw here as well. Since the clip attaches to the tail cap, it scratches against the battery tube when unscrewing the tail cap for battery changes.

The Streamlight Microstream provides good output for a light of this size. Running on a single AAA cell, the regulation is exceptionally well maintained throughout the battery life and drops sharply towards the end. Following which, the Microstream will go into a low power pulsing mode. The beam profile has a smooth narrow sized spot with a dim spill beam. Color of the light output is noticeably on the cool side, with some violet tint.

The Good - Well maintained regulation, good output and runtime running on a single AAA cell. Finishing is also very well done throughout.

The Bad - Push button switch has longer than necessary travel to click on. Bad clip positioning scratches battery tube when unscrewing the tail cap.

The Relative - Light has a cool color temperature, with slight violet tint.

Head (front view).

Body (side view).

Battery tube (rear view).

Tail cap (front view).

Tail cap (side view).

Tail cap (rear view).