FPVModel MC4010 580kv motors use the high quality Japanese NMB bearings and powerful N42sh magnets for optimal efficiency.
High quality meets affordability. You can find some reviews on the motors that made by independant 3rd parties at Youtube : https://www.youtube.com/results?search_query=FPVMODEL+motor.
Every FPVModel motor comes with a 30 days Satisfaction Guarantee. If for any reason you are not COMPLETELY 100% SATISFIED, you can return the motors for a full refund within 30 days upon receiving them.