Our Keystoker has the Direct Vent, it is a blower housing on the back/bottom of the stove, the 4" pipe extends thru the wall with a 6" collar around it (to keep it cool) and a Tee and cap. That is it. If you need pic let me know.
ALSO, our stove was designed for a direct vent, we ordered it that way, it vents out the Bottom back of the stove, so all the heat stay in the top of the stove. It cannot be used any other way as far as I know.
Also, makes it easier to fill the hopper, no top pipes.