OLight SR91

Two brightness levels and strobe mode
High Mode: 1500 Lumens / 3.1 Hours
Low Mode: 450 Lumens / 10.5 Hours
Strobe: 1500 Lumens / 10 Hz / 6.2 Hours
Max throw: 800 meters.
Anti-shattering, scratching ultra clear lens,
with 99% light transmission
Weatherproof: IPX-68 Water/Dust rating
Battery pack: 6 x18650 (7.2v, 6.6A)
Dimensions: Length: 11.34″
Bezel Diameter: 3.15″
Weight: 42.19 oz. (With battery pack)
Color: Black, Hard Anodized finish.
Mil-spec: MIL-STD-810F

First Impressions:
The OLight SR91 is considered the “little” brother of the SR90. The two lights are very similar. Basically, the SR91 has a smaller head/bezel and a reduced lumen output, with just alittle less throw, or effective range. So I recommend you read my review on the SR90 for more information on these lights. This review will just tough lightly on the differences between the two lights.
The main advantage the SR91 has over the larger SR90 is its smaller size and weight. It makes a pretty big difference when you are handling the lights. Dont get me wrong, the SR91 is still no small light, but it just seems to be much easier to handle than the heavier SR90. It seems better balanced with the smaller head/bezel. The body of the two lights are the same. They both even have the very useful built in charge indicator lights.

Build Quality:
Just like the SR90, the SR91 seems very well made, you could still use it as a club. The aggressive square knurling is great, and sure to provide grip in any condition, with or without gloves.

Output & Runtime:
High Mode: 1500 Lumens / 3.1 Hours
Low Mode: 450 Lumens / 10.5 Hours
Strobe: 1500 Lumens / 10 Hz / 6.2 Hours

While the SR91 may not have the output of the SR90, its still quiet bright, and has much longer runtimes, which may actually make it even more useful than the SR90 in some situations.
The beam pattern of the SR91 has a bit larger hotspot than the SR90. It also has more noticeable artifacts around the hotspot. But this is understandable, since it has a much smaller reflector.

Heat Issues:
Heat doesnt seem to be a problem for the SR91, it has a smaller bezel, but is also not driven as hard, so heat seems to be about the same as the SR90.

Smaller and Lighter than the SR90
More balanced and easier to handle
Longer runtime
Built in Charge Indicator

Only 2 output levels
Still rather large and heavy

I think the SR91 is a nice compromise to the larger SR90. While it is still a large and heavy light, it just felt much better to handle, and was less head heavy. I wish I would have had both lights at the same time to directly compare them though. Especially for output and effective range. The SR91 is nothing to laugh at, but I recall the SR90 being quite insane for an LED light.
One main complaint I have about both lights, is that they only have two output levels. While I realize they are meant to be high output long range lights, I see no reason they shouldnt have at least 5 to 7 output levels. This feature would make them so much more useful. You could get some killer runtimes from these lights if they had low modes down at 100 lumens or even less. You stand one on its tail and it will light up a room bouncing light off the ceiling really well. If they had much lower modes, you could easily use them as room lighting for a couple nights during a power outage.

These lights and more can be found at www.4sevens.com