Outside sealing plastic ring carrier seal units are used to seal ball and roller bearings against loss of grease and ingress of dirt or splash water. They are made from Polyamide 6.

Plastic ring carrier seals are also used for vehicle axles, other wheels, pulleys, drive systems in vehicles, construction equipment, fire engines, etc.

Some ring carrier seals are equipped with an additional sealing lip which comes in contact with the bearings outer race. This is advantageous where high levels of splash water are encountered.