Are gimbal guards safe to use when flying with the phantom 3 advanced or pro? Do they effect the sensors?

Those brackets do have the potential to interfere with the VPS, causing it to drop altitude suddenly. It would have to be a matter of positioning it properly in order to ensure it's not in the way. Be advised however, if the unit does perform an altitude drop and crashes while that bracket is attached, it would void the warranty of the aircraft.

I think he is talking about the bottom positioning sensor.  

They don't effect them they are out of the way of the vps sensor, they don't bother the one I have, plus they also stop the legs from spreading under a heavy landing - though never needed mine for that purpose

i never had an issue, but DJI did say there's a possibility of interference with VPS...

Here's what I got on my quad.. I stopped using the guard that's below, as I use gear extensions:
http://forum.dji.com/thread-92282-1-1.html

I did not know that DJI had a gimbal guard they made.. actually I did not know of many DJI made accessories....  other than chargers and such.... perhaps camera filters....

fans2d43ce12 Posted at 2017-4-13 10:24
I think he is talking about the bottom positioning sensor.

I must have read the post a little too quickly, my bad. I edited my post accordingly.

SimonH78 Posted at 2017-4-13 11:07
They don't effect them they are out of the way of the vps sensor, they don't bother the one I have, plus they also stop the legs from spreading under a heavy landing - though never needed mine for that purpose

' plus they also stop the legs from spreading under a heavy landing'

Which is actually a good thing, it helps absorb the shock of a heavy landing.

Making the heavy drone smack the camera into the dirt because the legs spread is not good..... - the gimbal already the built-in has shock absorbers for the shock of a heavy landing. Cause the camera is pretty near the floor! & thats one good reason for gimbal guards.

Im not sure if i should purchase one as i dont want my money to be thrown away by a crash! Plus i wont be landing on much surfaces with alot of rocks etc!