For composite and UPVC doors, From the Anvil recommend using their door letterbox which is supplied as a full kit and contains a tunnel and brushes to reduce drafts and insulate the door. The sleeve inside the letterbox also protects the door from moisture and masks the aperture cutting.

From The Anvil - 46554

• Overall size: 315mm x 92mm
• Opening size: 249mm x 41mm
• Fixing centres: 283mm
• Maximum door thickness: 72mm
• Minimum door thickness: 42mm

Supplied with matching SS bolt through fixings.