Abstract: A closure system including a polymeric split ring clamp and a polymeric lid for a polymeric drum. To maintain the integrity of the closure, the lid rim region is formed having an annular restraining notch which cooperates with twist inhibiting blocking components formed within the interior of a cooperating inwardly opening polymeric split ring clamp. The blocking component may be provided as a sequence of regularly spaced block-like protuberances located within the inward upwardly disposed region of the ring clamp. A secondary closure arrangement is provided with the split ring clamp which receives a polymeric banding strap to prevent one end of the split ring from disengaging with an associated pivot arm. When the split ring clamp is in a fully open or pre-clamping mode orientation, a capture groove is formed with the ring pivot shaft formed at one end of the split ring clamp.