Fly masks

I almost hate to say it, I might be jinxing myself but here it goes...all 3 of my horses have not destroyed their flymasks this summer.  Each one of them is still wearing the same mask they started with at the beginning of summer.  This is amazing to me.  Zoe usually goes thru a couple of them.  Sky gets about 2 a summer.  Skippy is the only one that seems to keep one mask thru the whole summer.  Maybe Skippy has been giving the other 2 lessons!