A word of warning for people who fly with prop guards and also use the supplied string to close the gaps between the guards. Yesterday I went flying and when setting up in the field I noticed the string was frayed at one of the holes it was threaded through. I didn't want to risk it breaking in-flight and the possibility of the string getting caught in a propeller causing it to stop and my bird falling from the sky so I removed the wire and flew without it this time. I kept the wire pretty taut and I always felt I heard a sound when flying that might have been caused by the string vibrating in the air stream caused by the props. Constant slight movement will eventually make some edge of the guard gnaw through the wire. Maybe a less taut wire? Not sure this will prevent it as that will also be able to move. Even tighter? Or perhaps not threaded through the holes but four individual pieces tied between the guards? Problem with that is you perhaps won't see any fraying until it breaks. But it will be shorter. Or perhaps smooth the edges of the guard holes? Maybe best use Kevlar or similar extra strong line? Whatever you do keep an eye on that wire. You don't want to find your crashed bird with a broken wire tangled in one of its props.