CRL's Shelf Supports for KV233 and KV255 Standards are designed to provide the flexibility needed for different shelf sizes and glass thicknesses. Simply place the Shelf Support in the desired shelf location on the Metal KV Standard and snap into place. To change the shelf location, remove the support and place in the new slot. A rubber mallet may needed to remove the support once installed in the standard. It includes a rubber cushion to prevent slipping or damage to glass shelf. They are zinc plated to prevent rust.