Prime-Line Self-Locking Shelf Support Pegs, 1/4 in. Peg x 3/4 in. Shelf, Plastic, Clear (4-pack) U 9398N - The Home Depot

These self-locking shelf support pegs are constructed from plastic and feature round fluted pegs designed for use with shelving systems. These pegs feature a lock-in tab that secure the shelf flat in the event of excess weight being placed on one side of the shelf that would otherwise cause it to flip or tilt. These self-locking tabs also provide a great safety feature for small children who might grab hold of the shelving, preventing the shelving from being tipped. To relocate the shelf at a different height, the lock tabs on the left-side or right-side must be depressed and held simultaneously while pushing the shelf upward on the same side. Note: A second set of hands may be required when attempting to relocate or remove shelving due to this security feature. These self-locking shelf support pegs are used by many manufacturers