Ultra-Glide™ bearing assemblies feature satin-smooth Delrin® sleeves. Delrin® is an industrial synthetic plastic material similar to nylon, and will leave no marks on the material being cut. Applications include solid surface materials such as Gibraltor®, SSV®, Corian®, Surell®, and Fountainhead®, etc. Plexiglas® & other clear acrylics; and plastic laminates. Not recommended for regular wood applications due to a higher wear factor. Bearing # 47709, 47725, 47726, 47731, 47733 include Teflon® dust shields. These bearings provide a better seal to increase bearing life while routing materials that generate very fine dust particles (such as solid surface).