<p>Two Doppelmayr guide rollers, and a Sharpie marker for scale.  (They are ski lift parts.)
These rollers are made of some kind of very hard plastic, apparently solid.  They're described as "Guide roller dia 155x50mm PA6G", part number 10066449.  The rollers are 155 millimeters diameter, 50mm thick, and the hole in the center is about 80mm.  They weigh 1.494 pounds, and cost about 82USD <i>each</i>.
</p>
<a href="//commons.wikimedia.org/wiki/User:Dbenbenn" title="User:Dbenbenn">David Benbennick</a> took this photo on July 13, 2005.
No machine-readable author provided. <a href="//commons.wikimedia.org/wiki/User:Dbenbenn" title="User:Dbenbenn">Dbenbenn</a> assumed (based on copyright claims).
CC BY-SA 3.0
No machine-readable source provided. Own work assumed (based on copyright claims).