Ra Lights are the current product line by HDS Systems, well known by flashlight enthusiasts for their innovative and very high quality flashlights. The head on the Ra Twisty is quite large relative to the entire light, in fact its length is about half that of the overall length. Up the front sits a solid and robust stainless steel bezel which protects the front end. It has a 6-point crenellation along its lip which allows for light to shine through when placed head-down. Branding and serial number are engraved along the outer surface of the bezel. I noticed that the bezel on my sample was slightly misaligned from the main head. Behind the bezel sits a thick, AR coated glass lens which is advertised as being shock mounted providing additional durability when subjected to impacts. The aluminum reflector has a rather fine textured surface, its nicely polished and texture is consistent and even. At a bottom of the reflector cup sits a unique LED which actually has 2 separate emitters. The main yellow surface emits white light, while the small dot to its side emits red light. Neither of the LED's are perfectly centered, this is probably a compromise for having 2 separate emitters using the same reflector. Despite this, the focusing of the white LED is very good though, as see from the image above. The rest of the head is made of aluminum and houses the electronics which are fully potted meaning it's protected against shock and water. The "+" contact for the battery in mounted on a stiff spring mechanism which also controls the light levels. Externally the head is totally finished with diamond textured knurling which provides excellent grip and coated in a very dark gray Type 3 anodizing. Threads on the inner surface of the head are cleanly cut with no cross-threading or grinding issues.

As its name implies, the Ra Twisty uses a twist switch mechanism for all its functions. The twist mechanism was chosen over a push button switch because it is much more durable and reliable than a push button, thus in-line with the overall ultra-rugged profile of the flashlight. The battery tube, which is also the main body, has the same knurled finishing as with the head and is slightly recessed which helps when held in a cigar-style grip. This knurling also really helps with grip when activating the light via its twist mechanism. The dark gray colored anodized coating perfectly matches that of the head. The inside of the battery tube is anodized as well. The "-" contact is also mounted of a stiff spring, like the "+" contact. These hold the battery securely in place, reducing the chance of the light flickering off and on when the flashlights is subjected to impact. Threading on the Twisty is thicker than those on most other flashlights, they are cut smoothly and threads on the battery tube and head mate well. A well-lubricated, thick rubber o-ting sits just below the threads which water proofs the battery tube, and also provides slight resistance for the twist action. Right at the tail end are 2 large holes machined onto an extruded lip which allow for lanyard and key ring attachments. This lip sits flat which allows the light to stand on its tail.

The durability of the Twisty has been tested and proven by subjecting it to 20 foot drops and being thrown at concrete, pavement and rocks. More details at the Ra Lights web site.

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

The Ra Twisty is available in different configurations which not only provide different types of output but beam profiles as well. The different output levels are accessed by twisting in the battery tube at various distances. From any on position, every quarter turn switches to the next mode. The model reviewed here is the Ra-85-Tr which has output modes in the following order:

Off > Low (Red) > Low (15 lumens) > High (85 lumens)

The white beam profile form the Ra-85-Tr has a defined, tight hot spot with a slightly cool color temperature. There is a relatively bright, wide and soft corona around the hot spot which gives additional peripheral illumination.The red beam profile is rather lopsided at close distances within about a foot. It evens out after this, and has a defined ringed profile which has a dark center and red light around the corona.

Regulation is maintained nicely with the Ra Twisty, in addition, it also has other features such as thermal protection and low battery voltage detection. You can see the thermal protection activating in the runtime graph on high mode below at the 00:17 mark, this runtime was done with passive cooling. The electronics then ramps down output to protect the light and user from the excess heat produced by the LED. The low battery voltage detection ramps the output down to a noticeably lower level which warns the user of the battery status, while still regulating output to maximize battery life.
Note: I didn't take control shots of the low red mode as it's too dim to be captured.

While officially the Twisty is documented as having 3 fixed output modes, it is capable of customizing a variety of brightness levels for each of the output modes. For details on this, click here.

[Update: July 07, 2008]
Runtimes on high mode have been updated to include tests done with active cooling (AC) and passive cooling (PC). This emulates the use of the flashlight in cold conditions. In normal ambient temperature, this shows the overall runtime you can expect when the light is used intermittently before the thermal protection kicks in.

The Good - Extremely rugged and durable, almost indestructible from general abuse. Simple and straight forward user interface. Allows additional customization if needed.

The Bad - Beam profile from the red LED has various ring shaped artifacts. Costs more than most other lights with similar functionality.

The Relative - Beam profile has a slightly cool temperature. Able to tail stand on flat surfaces. Uses a twist switch.

Head (front view).

Head (side view).

Head (rear view).

Battery tube (front view).

Battery tube (side view).

Battery tube (rear view).