Readytosky Prop Tool is a handy wrench for field servicing your drone. The prop wrench has a smooth running bearing that only rotates in one direction. Thus, one side is used for tightening the propellers, the other for loosening. The sides of the wrench then have a 1.5mm and 2mm Allen key, which will come in handy when making any repairs to the copter. The end nuts for the nuts are replaceable. Both M5 and M3 nut ends are included.