This is the HyperFlow 370 EP Ducted Fan Adapter. This is a Ducted Fan Rotor Adapter. FEATURES: Brass and steel construction INCLUDES: (4) 6.5mm OD washers (2) 2.6x3mm grub screws (3) Brass rotor adapters (1) 2.6x6mm phillips head machine screw (Silver) (2) 2.6x4mm phillips head machine screw (Black) REQUIRES: Assembly onto Ducted Fan Rotor Unit mlm 8.03.06 ir/jxs