Rating: 5 / 5
If I could have only one flashlight, or maybe even one lighting device, it would be the 5.7oz 5watt, 2xCR123A powered Surefire U2 Ultra Digital flashlight.
First the downsides:
1. How do you spell EXPENSIVE? Why "Surefire U2", of course ($279)!
2. The nearly 1.5" diameter head (not the barrel diameter which is smaller) of the flashlight makes "side" mounting using a Jakstrap-type headband doable, but not as convenient as with some other smaller diameter flashlights.
3. The very robust clip is backwards, and non-removable, so it can't be clipped to the STIFF brim of a cap or hat. It is solely made for clipping to a belt, waistband, or pocket for quick access.
4. The U2 is just a bit too long at 6.3" to jury-rig to the STIFF brim of cap, but it can be done - though it is not too comfortable; side-mounting is best.
5. Output intensity selector ring has no detents to aid in feel when selecting an output level. Hence, with the light off, other than MIN and MAX output settings, it is not possible to select other light levels.
Now for the upsides:
1. Surefire is one of the few Mfr's who: a) don't inflate their brightness/output ratings, and b) don't inflate their burn-times. They are conservative on both counts.
2. SIX different lighting levels easily chosen from a ring on the barrel of the flashlight. BLAZING light output on the highest setting.
3. LONG burn times on lower three output levels.
4. Excellent regulation.
5. Exceptional construction.
6. Very ergonomic tactical tail/butt switch.
7. One of the very best beam patterns that i've ever seen. it really has to be seen to be appreciated. one doesn't get the feeling that either THROW or OVERALL output were short-changed to enhance the other. a generously sized spot with more than ample throw on higher output levels. A perfect balance b/t throw and overall output, IMO.
8. a slightly crenallated strike bezel - useful if your trekkin' mate allows a branch to snap back in your face!! One sharp, forceful rap to the back of the noggin' or the temple area = problem solved!!!
Here are the Lumen outputs and burn times. Note that the burn times are Mfr. claimed and independent testing shows slightly better than Mfr. claimed. Also, the only published Lumen outputs are for the highest and lowest output settings. The other lumen outputs are estimated.
HIGHEST: 100 lumens for 1hr.
75% in ~52min; 50% in 64min; 25% in ~1:15; 10% in ~1:30; continues to produce dim output beyond 2:30
2nd highest: ~59 lumens for 2.5h
3rd highest: ~32 lumens for 5h
4th highest: ~17 lumens for 10h
2nd lowest: ~9 lumens for 20h
LOWEST: 2 lumens (Mfr claimed), but perhaps more like 4 lumens for 40h