Stainless Steel, Ceramic Hybrid, Orange Sealed bearings are specially designed for any application seeking a high precision, free spinning bearing. These are the true secret weapon for serious rc racers and long distance casters. ABEC 7 tolerances makes the Orange Seal line the closest precision tolerance that Boca Bearings has to offer. The removable, non-contact rubber seals results in a bearing with less drag and that requires less maintenance than a typical shielded bearing. The Grade 5 ceramic Si3N4 balls will allow the bearing to be lighter and spin 50% faster than a traditional steel bearing. LD = Lube Dry Bearings have been clean and are free of all grease and Oils. KIT (2) SR166C-2OS #7 LD.