Accessory plastic holder used with SPE, AP- DM, and AP-DH series shelf standards (all sold separately) to keep the shelf in position Sold as a set with one front and back shelf holder.WARNING: This product can expose you to chromium, nickel, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.P65WARNINGs.ca.gov.