Hy HyVIZ Reflector Exercise Sheet. The Hy HyVIZ Reflector Exercise Sheet is a great way to keep your horse warm during winter with its under-fleece lining. With its ultra-Reflective sheet, reflective piping and double reflective strips on each side and tail flap, ensures the ultimate visibility and safety whilst riding. This waterproof Reflector Exercise Sheet features a super snug fit for both the convenience and comfortability for both horse and rider, offering a seamless outline cut-out for the saddle to sit securely in with an adjustable touch tape strap feature that sits just in front of the saddle.