Like Flyingboats RCG stated these blade brings new life to the V912 and Fx71 mini helicopters. They should have came as a standard upgrade kit for those aircraft. One note however is that you need ot extend the tail boom so that the blades will not strike the tail blades. The process is very simple to do by either using a longer pipe or moving the factory pipe out and drilling a few small holes for the screws to go in. I think that these blades need to also called V912 upgrades because they are. Thanks Flyingboats RCG, if it was not for you I would not have found this mod on the Internet.