Double your work space. Hinged palette extension, with 5 holes to set brushes, and a parking slot for the hang-up brush caddy or handy hook (purchaseed separately) increase the flexibility of the thumbox. Basswood laminate and aluminum. Aluminum standoff keep it elevated above your palette when closed - no need to clean when you pack up. Easily attaches into existing pilot holes inside the right edge of the thumbox. (note: with the palette extension kit installed, you will only be able to carry one wet panel in the thumboxlid.). The item includes (3 wood screws, 1 machine screw and 1 aluminum threaded standoff)