Our XL Cambridge Premier Window Box is made premium grade composite cellular AZEK PVC that will not rot or mildew and is completely insect proof. It's built with an integrated cleat and bracket system that makes for a simple installation and long lasting stability. These XL Cambridge Premier standard size Window Boxes can be installed in minutes. The AZEK Premier composite PVC looks and acts exactly like wood. All of the "Premier" line of window boxes and planters come in standard white, but you can easily paint them any color to suit your need. You can even Faux decorate/paint them for added texture, color and effect. Brackets are for decorative purposes (not for support) and can be attached to the bottom of the box via PVC cement (recommended) or wood screws at your discretion - cement and/or screws not included. The front and both ends of the box is trimmed but the back is left flat for flush mounting to your wall. Our Extra Large size boxes are 10-1/2 wide and 10-1/2 high and the trim adds 4" to the overall length and 2" to the overall width and height.