This is the Ultimate Racing Clutch Bolt UR0638. Made of high quality steel and laser engraved. Designed with double head, the inside is 3mm hex and the outside is 5.5mm hex, so you can use a screwdriver wrench.
Ultimate RC Multibox with Lockable Lid 365x295x85 Sorting Box
Ultimate RC air filter foam (12) oiled for "AIRMAX" filter UR0529-12
Ultimate RC silicone spray hose transparent 2.5x6mm 25 meters
Ultimate RC Sensor Cable 75mm Flat (1) Flexible Brushless Motor
Ultimate RC 3mm Black Aluminium Stop Nut Self Locking (10)
Ultimate RC Silicone Oil 40,000 cps # 75ml