[gr8fl4porsche]

Any size will do the job, the bigger one will do it faster but is harder on the back. You have to lift it (or drag it) to move it to the next spot. They get real heavy, real fast. I used both on my project. Once you get the first chunk removed, the next pieces break off fairly easily.

It depends on how thick the slab is. At 2" the demo hammer is fine. 4" you may want the big one.