MINIATURE BALL BEARINGS. A MINIATURE BALL BEARING IS A TYPE OF SMALL ROLLING ELEMENT BEARING THAT USES ROLLER BALLS TO SEPERATE TWO BEARING RINGS OR BEARING RACES. PART NUMBER 693-ZZ, 693Z, 693ZZ, R830-ZZ, R-830-ZZ, MR693-ZZ, 693-2ZJ1 AND L-830ZZ. THE BEARINGS HAVE METAL SHIELDS ON BOTH SIDES AND ARE PRE-LUBRICATED. INSIDE DIAMETER: 3MM, OUTSIDE DIAMETER: 8MM, THICKNESS: 4MM.