bearins are divided into various types such as open,with single or double shields(A,2A) and with seals(RS,2RS).when double-shield or seal bearings leave the factory,grease has been filled in them according to relative requirements.upon being unpacked,these bearings can be directly put into use at the service temperature of –400C~2000C。When bearings need to work under special conditions,clients should enclose grease volume and brand name of grease or other requirements.