3″ & 2 1/4″ Trackball Bearing Kit (Set of 6 bearings) (MP1077). These fit and are used on all Atari, Suzo Happ and Wico 3 inch and 2 1/4 inch trackballs. Atari original part number is 035937-01 and other numbers these replace are R-4HH, R4-ZZ, R4ZZ, and many others that are 0.250 x 0.625 x 0.196 inches in size. Original and replacement bearings were only ABEC 3 rated or less and our bearings are THE BEST top of the line bearing that we had made and are ABEC 5 precision rated and are oiled and double shielded. These Ball bearings are a high-precision premium quality shielded deep groove, minimum grade 10 balls within this bearings, designed to reduce rotational friction and support loads. The load is spread evenly across the grade 10 balls, and as the inner bearing race rotates, so do the balls and the metal shields located on each side of the ball bearing keep the bearing lubricant in while keeping unwanted contents / contaminants out. Don’t settle for all those other supplier’s lower grade bearings because you will feel the difference in your arcade game play and see the difference in how long they last because we didn’t settle for okay but THE ABSOLUTE BEST.