These 12" 20/40 Letterbox for UPVC doors have been awarded Secured by Design approval by the Association of Chief Police Officers. Nanocoast lifetime coating guarantee. Outward facing brushes create the Anti-Vandal feature as it prevents vandals from placing unwanted items into the cavity. Outwards facing brushes also means better draught proofing and makes it easier to post letters through. 180 degree opening flap means the flap will not snap off when opened too far. Blind bolts to the exterior of the letterplate prevents the outer frame being unscrewed from the door externally. An internal water seal prevents water getting into the door or panel, and stops letters getting wet. Supplied with 2 fixing bolts.