SureFire Z2 LED CombatLight Flashlight [80 Lumens / 11 Hours ] Z2L-BK (http://amzn.to/1beJG5C)
I use to use the high output light bulb but the battery lasted only 20-30 minutes and now it last 12 hours.
I updated the tail cap to be a push button where it will turn on until pressed again.
It uses the CR123 lithium batteries from SureFire (http://amzn.to/1amTxTT). They are way cheaper than buying them from a local store.
It fits in the flashlight pocket on my 5.11 tactical pants (http://amzn.to/1eJhYN1).
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