Allen screwdriver set comes with a cross wrench can be used for removing and tightening hex screws hex nuts in rc car, rc helicoptor, rc boat, Multi-Axis FPV racing drones, robots, etc. Hex screw drivers come in handy, durable, sturdy and precise. Perfect tools for M2.5, M3 and M4 hex nuts. Total Length: 6.81inch / 173mm, Handle Length: 3.54inch/ 90mm, Handle Diameter: 0.7inch/18mm. Crafted from quality metal, no worry for rust or corrision. Easy to install, exquisite workmanship