The "puller" is a series of plates/hub you use. it pushes on the outer edge of the knuckle while it "pulls" the bearing through in the middle.
Part Source loans it out for free as well. both CT and PS have the "power built" stuff.
FYI, I had a lot of troubles pulling/pressing the bearing into place. when I was doing my alignment, the shop said my bearing wasn't in all the way and the my wheel was wobbling and can't do the alignment. they use a similar pulling/pressing thing to push it in.
the upshot of using the tool was that the knuckle can stay in the car (do not have to remove the ball joint) and don't need to do an alignment. I know ppl spray paint the bolts locations, but I haven't been able to pop the ball joint out of the knuckle without damaging the sleeves either