The standard DIN 9045 contains snap rings capable of use in like manner for external and internal retaining duty. This necessarily entails a gap between the two ends of the wire to permit installing as an internal retaining device, in other words when being fitted the snap ring must be capable of being compressed to the bore diameter. When used as an external retaining device the relatively large separation of the two ends of the wire means an unnecessary impairment of the retaining properties. This has proved unsatisfactory in practice, furthermore it has been shown that the best retaining action can only be obtained when the ring cross-section is accommodated to 50 % in the shaft or bore, as the case may be.