Instruction: ˇ´Use for T-REX 450 Pro. Specification: ˇ´Front drive gear assembly x 1 ˇ´Front long umbrella gear x 1(Φ2.6xΦ13.8x19.25mm) ˇ´Front short umbrella gear x 1(Φ3.2xΦ13.8x9.7mm)