Using the same quality standards as our regular steel bearings, these 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 Gibraltar, Corian, Surell & Fountainhead. Etc.; Plexiglas & other clear acrylics; and plastic laminates. Not recommended for regular wood applications Due to a higher wear factor. 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). includes new Teflon dust shields., #47733, diameter (D) 1, angle (a°) 5°, application new bowl bits., D 1/4, 47733 ultra-glide high performance ball bearing 1 overall DIA x 1/4 inner DIA x 5 Deg taper