Here's a closer look at the prayer wheels. There are 15 large wheels which turn automatically by electral power. The ones at Iron Knot run on solar. The small ones below you can turn by hand as you go around the building. Here's a quote from an online article about the prayer wheels: "The 3-ton, barrel-shaped cylinders are filled with rolls of ultra-thin paper that, if unwound, would stretch from Junction City (near Rigdzin Ling) to Denver. Close to 17 billion tiny Tibetan Buddhist prayers, called mantras, are inscribed on the paper. An additional 175 billion prayers on microfilm are in canisters inside the wheels..." You can see the whole article at http://www.buddhistchannel.tv/index.php?id=65,3105,0,0,1,0