Kaywoodies were famous (or infamous, to some) for their screw-in stems. However, they had a problem of eventually getting off-center because of the very slight wear to the fitment threads every time the stem was removed and replaced. Kaywoodie tried to fix this by making each pipe with a slightly off-center rightward cant. That is, if you held the new pipe in your mouth, the bowl would cant slightly to the right. As time went by, it would eventually line up dead center. Of course, as even more time went by, it would begin slanting slightly leftward due to continuing thread wear.
So Dr. Grabow (also famous or infamous, depending) came up with the "Ajustomatic" screw-in stem. Similar to Kaywoodie's, except that the screw-in fitment wasn't fixed as tightly and permanently into the stem. That way one could use just a little extra force to line up the bowl and stem at the desired angle. But if you fiddled with it too much, or it just wore out from age and use, it became very loose and you'd pretty much just have to go buy yourself a whole new pipe.
Since this ad uses the term "Ajustomatic," I must assume that Van Roy was another variety of Dr. Grabow.