Garver ceramic bearings are precision machined with an 8mm inner diameter. Made of hardened high carbon steel, accommodating the solid silicon nitride ceramic balls, nylon retainers and dual non-contact labyrinth seals amidst our specially designed lubricant, essentially modified turbine oil, a resilient bearing with a smooth feel emerges. Competition Calibre rated, far superior to ABEC, takes into account fracture resistance from drops and shocks, lateral loading from slides and hard carving and the ability to resist dirt and debris. Early in 2009 Garver began working with Carbon Neutral Company to offset all of the carbon produced by the manufacturing and shipping of these bearings. The result of our work means that Garver has a negative carbon footprint and when you purchase a set of bearings it helps fund wind power projects around the globe. These may very well be the last set of bearings you ever purchase. And at only $52.00, that's not a bad deal.