Very decent ball bearings. Slightly greased. They roll uniformly, with little toggle... I have to trust the seller that the quality and quantity of grease is as required because I don't own an ultrasound measurement device (Please don't over grease the bearings as too much grease creates pressure between the balls and the housing and leads to overhearing and damage. In fact too much grease is more catastrophic than no grease in most cases). One issue though: the outer diameter is slightly shy 19mm (about 0.07mm). I checked against ball bearings from 2 other manufacturers and they are much closer to the number before the decimal. I have attached photos of measurement of 4 different ball bearings in the batch I received from this seller. However, in overwhelming majority of applications this discrepancy is inconsequential... But I thought I should mention it...
Very decent ball bearings. Slightly greased. They roll uniformly, with little toggle... I have to trust the seller that the quality and quantity of grease is as required because I don't own an ultrasound measurement device (Please don't over grease the bearings as too much grease creates pressure between the balls and the housing and leads to overhearing and damage. In fact too much grease is more catastrophic than no grease in most cases). One issue though: the outer diameter is slightly shy 19mm (about 0.07mm). I checked against ball bearings from 2 other manufacturers and they are much closer to the number before the decimal. I have attached photos of measurement of 4 different ball bearings in the batch I received from this seller. However, in overwhelming majority of applications this discrepancy is inconsequential... But I thought I should mention it...