WARNING!
February 2006: There are counterfeit Surefire U2 flashlights floating around. You could run into one of these almost anywhere, but be especially careful at gunshows, flea markets, non-Surefire-authorized Internet dealers, or EBay. They could easily pass for a real U2 at first glance because they even have the actual Surefire logo and a serial number. However, they only have 2 levels of output, are relatively poorly made and the selector ring does not work. If you want to be sure to get a REAL U2 and not a $25 counterfeit, I recommend you buy only from a reputable Surefire Authorized Dealer! More info.

The U2 is the latest and greatest innovation from Surefire. This little gem is the culmination of years of design work and innovation which have led to an amazing light with output to spare and multiple levels of brightness.

The body of the U2 is solid aircraft aluminum which has been machined, checkered, and finished with Type-III hard anodize. Around the front of the bezel is a shallow scalloped ring with 5 flat plateaus which serve to show that the light is turned on when placed face down by allowing some light out around the bezel edges. Below that is the key feature that makes the U2 very unique. A polymer ring, textured with ridges and deep grooves sits below the head. By rotating the ring you can select any of 6 brightness levels which give a variety of runtimes as well.

A spring steel clip is attached at the bottom of the body just before the tailcap. This is another unique feature of the U2 in that it is the first Surefire I am aware of that is designed to be carried bezel down. The surface of the light body is machined smooth under the clip to help prevent undue wear of the pocket in which it is clipped. O-ring seals protect the light from water entry at both ends.

The U2 has a deep textured reflector which catches the light from the single Luxeon V (5 Watt) LED. The head contains a slightly domed pyrex lens and a regulator circuit that provides constant light output from the LED during the working life of the batteries.

Output is very good, with more overall output on high than the 2 cell Surefire incandescent lights. The beam is very usable, with good throw and a great spillbeam. The beam is very white, despite the bluish tint seen in the photos below.

   
Beam at one meter at target center and at target edge to show spillbeam.

The runtime plot on high shows about 1 hour to 50% brightness. Third party individuals have completed runtime plots of the other output levels and the regulation is very flat on all but the highest level (shown below), which declines slightly.

Runtime completed with included Surefire batteries. More information on runtime plots is available HERE.

The switch on the U2 is a clickie switch. Press the textured rubber end button for momentary activation, press until it clicks for constant-on. Twisting the tailcap backwards locks out the switch so that accidental activation is prevented.

The entire light is sealed with O-rings and is waterproof to 33 feet according to Surefire literature.

Ergonomics: Easy to handle and use. The brightness ring is difficult to turn with the same hand as is being used to hold the light, but it is possible. Surprisingly lightweight.

Size compared to a common 2AA aluminum light

The U2 takes two 123A lithium batteries. These batteries are very expensive even at national discount chains but can be purchased online at Surefire.com for around $15 for 12 batteries at the time of this writing. To change the batteries, remove the tailcap, dump out the old batteries and drop in the new with the positive terminals pointing up toward the bezel end. Reassemble and you're ready to go.

What I Liked: Very bright, tough finish, Shockproof LED, No bulbs to buy, Multiple selectable light levels, Waterproof.

What I Didn't Like: Nothing

Other Things I Noticed: Nothing

Conclusions: What can I say? Another great light from Surefire! Very bright on "high" but able to change output in an instant to a lower level to match your needs or battery conservation requirements. A fantastic light all around.

Quick Facts Table: