I have a 70x 200 riding arena that has an imported OTTO brand sand/fiber mixture 3-4" deep on top of rubber finger mats. Looking to remove it from the arena and sell it. It is very high-quality material. when you lightly wet it down it holds that moisture for a couple days and makes lovely riding surface. I believe it to be a professional OTTO Euro-Sand/fiber mixture because I have been told it was imported from overseas it performs excellent!