Harken Replacement Ball BearingsHAR176
Harken replacement ball bearings are for use in Harken blocks, cars, and cleats. The ball bearings come in various diameters and two different materials.
Delrin ball bearings are well-suited for low- to moderate-load applications.
For high-load applications use Torlon ball bearings.
Not sure which ball bearings you need for your Harken product, use the below link to identify the proper ball bearings.