While most flashlights are stuck to the specifications from the factory,
P60 hosts allow you to modify/upgrade them. As you can see in my last video,
a P60 body comes apart. You have a variety of LED's(bulb as an analogy) to
choose from, some aren't even in existence yet. As LED development
continues, you have a chance to take advantage of future technologies:

http://www.batteryjunction.com/p60-dropin.html

You have a choice in brightness and also modes, on/off, lo/hi/flashing,
lo/med/hi, etc. That particular flashlight in my video has the ability to
go from one 18650 battery(two CR123's) to two 18650's(4 CR123's) to
a maximum of three 18650's(6 CR1213's) since it has extension tubes.

You can choose different heads, one for more throw or one for a bigger
spot pattern. Head bezel can be smooth or crowned(for tactical/defensive
use). Switch can be exposed(easier to use with winter gloves) or crowned
(tactical use, again). The options just go on and on.