From @Tahoe Ed posted on rcgroups: WARNING! DJI LA has received several returns about Phantoms that fell out of the sky without warning. We have investigated those cases. In many of them we found that the users have installed third party prop guards or after installing DJI prop guards installed the prop guard screws after removal of the guards. The third party screws were too long for the installation as were the DJI screws if the prop guards were not installed. This has caused the screws to contact the motor causing it to fail. This is to inform all DJI users that the installation of third party prop guards will invalidate your warranty and the misuse of the DJI prop guards will also invalidate your warranty. Please use the screws that were provided with the motors. If you use DJI provided prop guards then make sure that you install the original screws when you remove them. I hope that this clarifies the use of prop guards. The DJI provided prop guards work when used as proscribed by DJI. Be conscious of the screw length.