Review on Milwaukee 49 56 0132 4 Inch Hardened Hole by Stephen Parkell

I need to drill a 2-1/4" diameter hole in the wall. I ordered and received this 2-1/4" saw (that's what it says on the box!). But the saw is 2" OD - how does it make a 2-1/4" hole? I have other Lennox saws, always found them ok, but the exact diameter wasn't important to me at the time I guess. :-(