Specifications: Tail rotor hub x 2 Tail Rotor Washer(Φ6xΦ8x0.3mm) x 4 M4 set screw x 2(M4x3mm) Socket collar screw x 4(M2x6mm) Weight:14.4g Instructions: 6061-T6 Aluminum alloy material and CNC processed。 Use for T-REX 500EFL / PRO /DFC Must with: 500PRO Metal Tail Rotor Holder(H50119B)