I need clamps to fit on a 2 inch tower. I'm guessing either 2 inch w/ inserts or 1 7/8?? I don't know how big the diameter is on the inside of the 2 inch clamp.
Here's their actual site, it's under construction but it has all their contact info so you can order direct from them http://www.precisionmetalworksinc.com/index_files/page0003.html. And Mike's right, 80feetout.com has the exact same clamps for pretty cheap.