NSK 6404ZZ Metal Shielded Deep Groove Ball Bearing 20x72x19mm

Metal Shielded Deep Groove Ball Bearings: One of the most commonly used bearings, these types are manufactured with metal shields inserted into the outer raceway, these fit in closely to the inner race providing protection against light mechanical damage, some protection against the ingress of moisture, dust and other foreign matter and serve to retain the pre-filled grease in the bearing.
Shields can be removed for applications that don't require a shield or only require 1 shield.

Benefits: Provides light mechanical protection, limits moisture and dirt ingress, lubricated for life, cost-effective solution.