25 x 37 x 6 Stainless Steel Sealed Premium ABEC-5 Ball Bearing Silicon Nitride Ceramic Balls 25mm x 37mm x 6mm 25 x 37 x 6 Stainless Steel Sealed Premium ABEC-5 Ball Bearing, bearing is Silicon Nitride ceramic balls, inner diameter is 25mm, outer diameter is 37mm and width is 6mm.