it's just a little tile bit that, you can find them at menards. it goes to a dremel. As long as your tank isn't tempered shouldn't be a problem, Also I would suggest getting a schedule 80 bulkhead since the flange is a little bigger there is more room for error on the hole. The hole won't be a perfect circle but it will be close. I've done over a dozen of them with no problem. What size hole are you wanting to drill I have a bunch of different size sch. 80's. that I can sell you for whatever I paid for them at Savko.com