"E" Style, Radial Mount Retaining Rings are popular and widely used. The three prongs of the "E" profile make contact with the bottom of the groove of the shaft and provide a shoulder for effective retention of assemblies. The 2133-5133 family of External, Radial Mount Retaining Rings are available in shaft diameter sizes between 0.062 and 1.375 inches, and groove sizes between 0.052 and 1.230 inches. Ring thicknesses are between 0.010 and 0.062 inches. Most "E" rings can be installed by simply pushing them onto the slot on the shaft, using mounting pliers/installation tool.