To provide large shoulders for positioning and maintaining machine parts. They are applied radially and are locked positively in their groove by means of two prongs extending from the inner circumference to the open end. They withstand high thrust loads and relative rotation between the retained parts. Their bowed construction provides resilient end-play take-up in axial direction. They may be assembled and disassembled with a screwdriver or with the prong-lock applicator. Sizes .125 to .312 are available rod-stacked for high speed application. The use of the following formulas are based on the fact that the ring material will not fail in compression. Limitation on use - the following formulas are not to be used for brittle materials such as cast iron, etc.