WORC WRC354B Brushless Motor ESC 3.5mm Male to 4mm Female Bullet Connector Adapters (3)

 Connector Type:3.5mm Banana Plug to 4.0mm Banana Plug(Male to Female) 

3.5mm Male to 4mm Female 

Solderless / Wireless

3 Pack 

Traxxas Velineon 3.5 Most aftermarket 1/10 BL motors use 4mm

Great for upgrading motor on Traxxas VXL