This is a genuine Ryobi replacement part, it is sold individually.
The purpose of the 039066005050 Spring Clamp is to clamp the sandpaper to the platen of the sander.
Once the sandpaper is placed on the sander the spring clamp is pulled up and attached to the side of the platen to secure the sandpaper.
If you want to order the spring clamps already attached to the Platen you can order part number 039066005054 Platen Assembly.