It is a redesign of the mag mount, wind barrier, and stepper mount. It exposes the stepper motor so there is more surface area exposed for radiant cooling. It also adds a vent for the extruder gear for better cooling. Cooling of the gear will hopefully prevent jams due to the gear melting the filament. The wind barrier changes include redirection of the hot air and better sealing around it for better fan efficiency. The wind barrier is an older design of mine and works quite well.