At the time these Emax Eco were chosen as they were the standout budget motor. They have been available for $10-$12 and based on how they perform represent outstanding value - the top equal standout recommendation for this parts list. Emax had the original breakthrouhg brushless motor in the quad scene - the RS2205s which changed the industry. While others have caught up since they still make well-researched high quality motors. The Eco series draws off the learnings from the LS and RS2 series - they remain VERY light but have increased the bearing size from 8mm to 9mm to improve durability significantly. Retained from the RS2 and LS series however are the thin magnets. Although these mean the motor doesn't make the same peak thrust as heavier motors with larger magnets, it does gain in improvements through being lighter, more efficient and smoother at throttle transition. This makes it a great match to freestyle where these positive attributes tend to be preferred over peak thrust @ 100% throttle. In use these are very nice motors to fly. They are quiet, smooth and cause less battery sag and longer flight time than more expensive motors I use such as the brother hobby returner R6 2306.

Interesting that based on the success of the Emax Eco, iflight and brotherhobby have followed suit. 3bhobby also have the training motor although this may have just been out when the emax eco was launched.