For any noobs like me that will be drilling a hole in their keggle for a ball valve for the first time, don't be intimidated. I was worried to death because i thought stainless steel was going to be really hard to drill with a hole saw, turns out it isn't. SWMBO picked up a 7/8" Dewalt Impact Ready Hole saw (part # D180014IR) for me today. I measured (twice ) and center punched for the hole. Then, as a bead of sweat began to drip from my forehead, I started drilling slowly. 10 seconds later, my hole was finished. I am still amazed at how well this saw cuts. I am not sure if other methods work just as well or not, but I just wanted to let you know how well this did. Happy Brewing!