If you are connecting two pieces of shelving together then you will need this piece of hardware! This joiner plate screws together and locks the CloseMesh shelving into place so they sit next to one another and form what appears to be one continuous shelf. You can not use a 1003 joiner plate to attach CloseMesh shelving together and you will be unable to use a 119 joiner plate to attach any other ClosetMaid shelving together except for our CloseMesh range. The joiner plate is made from steel with a white painted finish.