Eliminates insect-driven head tossing, caused by flies. Also, shields against potential infections by protecting the eyes and ears from flying insects.
All the Cashel masks are great. Sure, they come off as easily as all the other brands, and I've tried all the brands! But it is mostly a fit issue in my experience. Put it on snugly, and it pretty much stays put. I like the soft ears, must less irritating to my horses. Long nose version is great for sunburns, but does get a bit hotter.
I ordered horse size which was actually way too big for the intended horse, but it stays on anyway. I have been using it for 3 months with no problem. I am however going to put that one on my other horse with the larger head and order the Arabian size for the other. This is a good fly mask.
Even when my horse was in a paddock by himself he still managed to get it off. When he was out with other horses I stopped bothering with it, because I would have to search for it on the ground shortly afterwards.