I found these simple prayer wheels in Kathmandu. walking around the Boudahnath Stupa, i saw more of this simple copper prayer wheel than any other style.

Hand Made in Nepal, This prayer wheel is made of brass and copper with a wooden handle. Prayer Wheels are used daily by monks and laypersons alike in all Tibetan Buddhist communities. Inside the prayer wheel are scrolls containing this mantra. Every time the wheel is turned it releases all of these mantras into the heavens.
Size: 10 inches long