5x11 Dual Shield Ball Bearings (10) 5x11x4 MR115-RZ Includes Ten (10) High Speed Precision Steel 5x11 Ball Bearings. These bearings are perfect for any applications where 5x11x4mm MR115 ball bearings are required. Advantage Ball Bearings are perfect for a variety of applications including: RC Cars, RC Helicopters, Bicycles, Fishing Reels, Robots, Spinners, Inline Skates, Skateboards, Scooters, Tools, Machines, Vacuums, Electric Motors, Nitro Engines, Drones, Yo Yos, and more! The bearings are sealed by a Rubber Seal on one side, and a Metal Shield on the other. The Rubber Seal protects well against exposure to dust, dirt, and moisture, which can destroy bearings...while the metal shield provides moderate protection on it's side, but provides minimum resistance for maximum efficiency and speed. These bearings offer maximum protection one one side and moderate protection on the other, and have less overall resistance than standard rubber sealed ball bearings. Advantage Racing Product Bearings have been run by some of the fastest RC Car Racers in the world and have won multiple ROAR US National Championships. Over 250,000 bearings have been sold to satisfied racers all over the world!