The 910H 19* is the one that replaces the AP1 3 iron. Because of the loft on the 3i is 23* I thought that was strange when the guy at the store told me, so I asked a Titleist rep at a demo day, and they confirmed that this is the one that is supposed to replace the 3i. Having said that, when I hit my H really well I hit it a ton farther than the 4i, so the gap is a bit bigger for me. The best way to tell, for you, is to get fit.