I've never heard them described as XF, IL or HD, but the 150 pro set comes with Fine, Medium and Coarse Needles and tips. Coarse is a illustration size and wouldn't find a use in modeling. Fine is, well, fine and should provide a hairline and Medium is the one I use 99.9% of the time. The siphon feed is all right, requires a bit more pressure is all. I have a 150 that is at least 20 years old and the other is less than six months, other than a small design change (the old one has a round enclosed end on the back side of the handle) they are completely interchangable. A fine testament to the original design.