Correct, this is a tool free assembly – no holes are needed in the cones.

As the compost heats up, the air in the tubes rises, creating an inflow of air from the bottom of the composter.   The air then travels up the center pipe to the bottom of the cone.  The cone does not have holes, so the air flows out on the underside of the cone where the tube connects.  The ribs on the cone then allow the air to flow out under the bottom rim of the cone into the surrounding compost.  Some will also flow around the first cone and up into the second tube – when it reaches the second cone, the same process happens, and air flows into the surrounding compost.  If there were holes in the cones, then air would only flow through the tube and out the top – never reaching the compost in the center.