Abstract: A split ring clamp for retaining a lid upon an enclosure such as a plastic or fibrous drum is provided which is formed entirely of polymeric material such as a high molecular weight, high density polyethylene copolymer. The assemblage includes two parts, a channel-form split ring and a pivot arm joining the two ends of the split ring together over the rim structure of a container. One end of the ring supports an integrally formed pivot shaft receiving notch as well as an outwardly extending toe with a rearwardly disposed contact surface. The opposite side of the ring is formed having a receiver channel within which there is provided an inwardly depending toe with a rearwardly facing contact surface. The pivot arm is formed having a transversely disposed arm pivot shaft and a ring pivot shaft receiving notch having a shaft access opening which is outwardly disposed and extends to a shaft bearing surface. Such an arrangement permits a more thin profile for the ring and pivot arm assembly.