1/4 x 3/8 Metal Shielded Ball Bearings (10) R168-ZZ Includes Ten (10) High Speed Precision Steel 1/4x3/8 Ball Bearings. These bearings are perfect for any applications where 1/4x3/8x1/8mm R168 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 Metal Shields provide moderate protection, but provides minimum resistance for maximum efficiency and speed. 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!