Portable Skf Ge50es2rs Double Sealed Radial Spherical Plain Bearing 50x75x28x35mm With A 35% Price Cut [OudX5skJ]

This series is classed as radial spherical plain bearings. Made up of sliding contact surfaces of steel against steel and also steel against brass. Bearingtech offer these bearings spherical plain bearings in sealed and unsealed and therefore some maintenance and some don't, the maintenance is in terms of re-lubrication from the sides of the ball. 

Some of these bearings will look like the out raceways are cracked or split, however this is a normal part of the manufacturing process and is a viable bearing still.