Sealed Bearing 5x8x3 Miniature5 x 8 x 3 Sealed Ball Bearing One Bearing 5 x 8 x 3 Sealed Ball Bearing, made from durable 52100 alloy steel, commonly known as chrome steel, each bearing is rubber sealed from both sides to protect the bearing from dust or any possible contamination, plus its pre lubricated with grease so its ready to roll right away. 5 x 8 x 3 Ball Bearing Deep Groove Ball Bearing Material: Chrome Steel Shields: 2 Rubber Seal Lubrication: Pre lubricated with grease