The skids featured in kickoff were made of teflon. Comming from team 263, I have much experiance in this field since for 2001 2002 and 2003 we had 2 wheel drive robots with 2 (or 4) teflon skids strikingly similar to the ones in kickoff.
They work extremely well for quick turning and as a slider for climbing things such as....maybe a step? We used them in 2001 to pull the back of our robot up over the 3 inch step under the 14" bar and never had a problem. If you are to use teflon skids, I would suggest reinforcing them with aluminum behind them to better support the wieght of your robot and if they'll be involved in climbing its always a good idea.