Installed on the underside of a shelf at least 14mm thick, this plastic insert has built-in spring flippers that grip a steel dowel mounted on the carcass to keep the shelf firmly in place.
The inserts are sold in packages of 20 with a matching number of dowels; the dowels have either a smooth pin for standard 5mm holes or a Euro screw thread (which also fits 5mm holes) for more secure installation.