Yes, Lansky is "inclusive". When you get your Lansky, each side will have guideholes starting at 17 deg (34 deg inclusive) and on up. It's out in the shop right now or I'd run out there and tell you all the angles it has. I used only the 17 to rebevel an edge...the others are too steep for anything else knife-wise (that I'm aware of). Then I turned to the Sharpmaker's 40 degree setting for a secondary bevel and final sharpening. So, in case this is confusing, my RAT-3 is honed at 17 degrees each side, with the final edge (or maybe micro-bevel) at 20 degrees each side.
I wish the Lansky had a setting for 15 degrees, but it doesn;t. I've been thinking though, depending on how you clamp the guiderods into the stones, you could very well lower the setting to 15 degrees or below. Haven;t tried it yet, though.
EDIT: I have the Deluxe....npt the Porfessional. I'm almost positive the Lansky Professional and Deluxe are the same, with different variety of stones. Your Professional's lowest setting will be 17 degrees, then 20, then 25, etc. Those settings ARE NOT inclusive angles. READ: 17(34), 20(40), 25(50) etc etc