This fan is currently the best 40mm fan available for someone wanting maximum rpm, thrust, and speed. This fan is stronger than the gws variants and uses a 2mm shaft adapter (part # 40adp28b) that won't spin off like the press fit rotors. The setscrew is 2mm and a 1.6mm screw is needed to attch the adapter to the rotor. These must be purchased separately (not sure why). I would recommend a 20mm inrunner in the 5000-8000kv range for 3s. The newer gws shrouds setup for 20mm motors are easier to work with compared to the aeorc shroud. I am not sure whether hk carries these shrouds but they are available elsewhere. This will make for hassle free, high performance 40mm edfTruly is Tiny.
Needs detail cleanup as the molding is mediocre.
Strange that this thing is More $ than the better made GWS rotors