DetailsQuality Cornerstone Letterboxes, with metal fittings. Quality 1 piece Letterbox. Available in Basalt, (greyish colour) or cream. Carved stone Texture Letterboxes. Made from Cornerstone, a lightweight composition that is both strong and long lasting. The Letterboxes are Lockable and come with keys 330mm w x 280mm x 900mm high. Pick up only.