SKF 618012Z Metal Shielded Thin Section Deep Groove Ball Bearing 12x21x5mm

Metal Shielded Thin Section 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 only require 1 shield
Benefits: Provides light mechanical protection, limits moisture and dirt ingress, lubricated for life, cost effective solution