Type: Full Ceramic Thin Section Deep Groove Ball Bearings Size: 4" x 4 1/2" x 1/4" Inch Inner/Outer Races: ZrO2 (Zirconium Oxide) Ceramic Balls: ZrO2 (Zirconium Oxide) Ceramic Cage: PEEK Closures: Open Full Ceramic Thin Section Ball Bearing 4" x 4 1/2" x 1/4" inch FCVA040CP0 is Full Ceramic Thin Section Deep Groove Ball Bearings with a 1/4" cross section width, inner diameter is 4" inch, outer diameter is 4 1/2" inch and width is 1/4" inch.