I just received a nice little package, literally. I ordered a Four Sevens Quark Mini 123. The specs can be found here:
http://www.foursevens.com/product_info.php?products_id=2856This is an amazing little light that runs on a CR123 battery. To be honest, a light using that battery is not my first choice, but when you compare the size with the light output and the run time, I just had to get it. One reason for buying this is to use it when I go out to exercise. I like to get out around 0600 and it is just too dark at that time. At work we have a large property that we can walk/ride around. Most of it I can get around without a light because of street lights, but there is an area that you walk thru the woods and it is just flat dark in there.
This light, weighing in at only ~1.2 ounces including the battery, is very easy to carry and when I don't need it I can just throw it in my pocket. At work I often carry a pocket protector and a lot of times I remove it because I hate the weight pulling my shirt down on one side. This little light I can toss in my shirt pocket and not even notice it.
The lowest setting of 3 lumens is perfect for shedding some light on the trail. It easily lights up about 10 ft. in front of me. It can go out to about 30 ft to show you whats out there but it isn't very bright. I can take care of that by switching it to the middle setting of 40 lumens and that is plenty of light to see out easily to 50 ft. At 3 lumens it will last for 150 hours, at 40 lumens it will last for 8 hours. Now if I had to I could switch it to the max of 180 lumens for up to 1.2 hours but it isn't really needed for that purpose.
This light functions using a twisting action, not a clicky. Turn it clockwise to turn it on low, back it off an 1/8 of a turn (or less depending on how you do it) and then turn it clockwise again to get the middle setting, and do it one more time to get high. If you want to get to the special functions you quickly run thru that series twice (low,med,hi,low,med,hi) and then twist it one more time and you get the strobe, one more time to get the SOS function, one more time for the beacon hi and then once more for the beacon low. The beacons flash every 10 seconds and the Hi will last for 12 hours and the Low will last for 60 hours.
A neat little feature I just figured out this morning, and I haven't seen anyone that has mentioned this in all the reviews I have seen, is that once it is on, if you just barely turn it to the off position you can then hold it cigar style and press the back and use it as a momentary type switch. Just be sure that you don't leave it that way and put it in your pocket as you are certain to turn it on and wear out the battery.