I purchased a 1- 1/8" drill that I used with a standard 3/8" electric drill. It is a bit of a challenge to start the hole if not using a guide drill. I was lucky and the first material I was drilling through was stone. It had an irregular surface so I could rest the drill against a protrusion on the stone and start the hole. Behind the stone was cement board, fire brick and then solid concrete. I drilled two 18" holes, I also purchased an extension from your firm, and didn't have any trouble. I stopped every once in awhile and pulled back on the drill to cool it and also remove some of the waste material. About half way through I removed the drill, dipped it in a bucket of water, attached the extension and proceeded. I ended up drilling an extra hole and then sealed it up just in case I need another one in the future. I have never needed one of these in 40 years of construction and don't think I will again but it worked fine. My suggestion is to perhaps start a rental program for extensions and other accessories, for guys who will only use it once. Or sent up a program to return the items purchased for a 10 or 20 percent credit. Maybe include drills, if there is a way you can determine how much "life" remains to the drill.