or you can just take the original drive dog and screw it together with the gear works very well and it will cost you 2 screws, 2 washers and 2 locking nuts :)
Radek
V4 D8 - RX8, XERUN 4168SD
F1-09 - Tekin RS Pro, 17.5t Redline, 2S LiPo
Sakura Zero S - LRP, Saturn 20T, 2S LiPo
*EX-10 Eurus*