This is an adapter \ connector for the Bosch ps50 (and possibly other tools that use the same head). This allows you to use any sandpaper that you cut to size instead of the standard triangle Velcro pieces . I've also included the source file for the connector so you can make your own heads. If you use it to make new tool heads let me know! It is a remix of the flat and right angle sander. There is a large right angle sander and a small flat sander.