A set of Hex wrench that will come in handy when building and servicing the copter. The set contains 4mm, 5.5mm, 7mm and 8mm wrench .
You can use the 4mm wrench mainly for smaller copters that use M2 nuts. The 5.5mm wrench is suitable for 5-7" copters, where you can tighten the classic M3 nut. The 8mm wrench is suitable for tightening M5 nuts on propellers.