Lithium 18volt.

I've replaced one defective battery and the two that came with it are already pretty anemic(nearly 2 years old). New batteries are expensive, they go up in price as they evolve... I've fixed the charger once(myself), come to think of it.

Standard cordless dependability, always dead when you need it.

As cordless tools I've owned over a few decades go, on a scale of one to ten, I give an 8. I keep a 20 year old makita screw gun on hand at all times. It has a cord.