The one I currently use has 2 aaa batterys and a small halogen bulb. It clips on to the bill of a cap. It works well for treestand instalation, deer gutting and monkeying with my gear on the tail gate of my truck.
I have another one I don't use. It has an ultrabtight red LED and uses two hearing aid batterys. The batterys die really fast. It also clips on the hat bill.
I also have small hand held light with a halogen & 2aa batterys. This casts a long beam. It is good for navagating in the dark.
Ever since I've bought my headlamp, I wouldn't ever try to drag/gut a deer without it. It makes life soooo easy. Of course, I still use my mini Maglite w/LED conversion kit when walking in. Not quite as bright as the headlamp so I don't scare as many deer.