This is a magnetic slide on base plate for FF AD3 3D Printer.
Its got an excellent buildtak surface on it which provides excellent part adhesion & good surface finish.
The metal sheet is removable & slides into the bed & gives you a new build surface to 3d print on.
Its good to replace these plates as & when needed to get optimal auto correction & auto level to work, depending on how much 3d printing you are doing.