So I printed these and used them a few days ago.... and for some reason my Phantom leaned backwards on takeoff and the rear rotors hit the ground... happened when taking off in grass, which I've done before... brought it to hard dirt, tilted a bit, then took off. Needless to say I took them off right away when I was done flying. Maybe it made my Phantom off-balance??
I have basicly the same type of snap on extensions and take off from all kinds of surfaces without any problems. Mine are a little longer then the landing gear as you can see in the photo. Landing gear measurements are 5 1/32 and the extensions are 5 3/32 inches long. A 1/32 of an inch on each end isn't allot but there is more surface on the ground whether that makes a difference or not.