The Restroation Equine Mask comfortably blocks blue light rays from entering your horse's eyes, allowing him to sleep, even under show conditions where the lights are typically left on 24 hours a day. Thus, raising melatonin levels and improving your horses performance. It's also handy to protect healing eye injuries. The masks block 100% of UV light making them the perfect solution for horses with UVitis. This model covers the left eye with a patch.