Mine has the built in battery. Its beat to death,has hit the floor 100 plus times. Underhood thing works well, and i have used it in cars, roll back windows down and hook it to roof. Slide along bar and point it directly where it will blind you the quickest.Speaking of lights, my local Snappy dealer is running a sale on the under hood lights. The ones that extend and clamp to the sides of the hood. Do any of you guys use them? Do you like them? I have a couple magnetic lights that I just attach to underside of the hood and they work great. The only real advantage I see to the Snap On version vs others is that it uses same battery I already have a million of? Not sure it is worth the cash.
I use it daily, and battery has held up perfectly.