Miniature Thrust Ball Bearings
Used to bear axial loads but not radial loads. Supplied as a ball race with two end plates that sandwich the race between. All but the smallest sizes have a groove in the end plates that the ball bearings ride in. Item title is quoted as internal diameter (d) x outer diameter (D) x thickness (H). Note max rpm is quoted based on oil, max speed will be reduced if used with grease.