Most flashlights come with a cheapo stock bulb.
But you can go to a Radio Shack or other electronics outlet and usually buy a Krypton bulb of the same voltage that will give you a lot more lumens.
Remember, though, the brighter the light, the quicker the batteries give out!
LED is the only kind of light worth having, (and I think Tolerance has a cheap, or older model, or a small battery version of one).
Look what this light can do with a single AA battery. A Krypton bulb can't do this.
http://www.fenixlight.com/viewproduct.asp?id=176
You should see what they can do with 4 AA batteries (and an led)!!!
http://www.candlepowerforums.com/vb/showthread.php?347951-**NEW**-Nitecore-EA4-Pioneer-(4*AA-860lm)
I converted all of my Mag-lites to CREE LEDs.