Grade-Up Parts Series no.519 HG Round Hole Ball Bearings (4pcs.) Item No: 15519 ★Precision ball bearings have excellent efficiency and minimal resistance. ★Use them on drive shafts, counter gears and the like for a smooth, powerful drive. ★Outer diameter: 6mm, inner diameter: 2mm, thickness: 2mm Information is correct as of November 5, 2018. Specifications are subject to change without notice.