Almost everybody is facing part cooling issues on Ender 3 when printing slightly faster. Instead of adding more fans on the printer head where it adds weight and make it sometimes ugly huge to be effective, this puts the blower on the side of the X axis beam and so it isn't putting any more weight on bad places while still adding much more cooling capabilities.
FEATURES:
BAD FEATURES:
ATTENTION! - As this is not placed close to the nozzle with very focused air stream, it blows some air on the nozzle and heatblock as well and you have to count with that - if you run the fans 100% and start heating the nozzle it will take longer and you could get thermal runaway error. Just wait for the nozzle to heat up or run the fans lower. When the nozzle is heated it holds temperature even at 100% fan.. but test it with your setup.
The author marked this model as their own original creation.