To replace your old letterbox you need to first establish which of the three sizes it may be: 12" Standard, 12" Slimline or the 10" Standard. The letterboxes are usually held in place by two or four screws under the inner letter plate. If you remove these the letter box will come apart. This will allow you to check the size of the hole that has been cut through the door. Once you know this information then check the details of the relevant letterbox. In some cases there may be some minor modification needed of the hole in the door but the letter boxes we show are the best sizes available to fit all known letterboxes. These letterboxes are all covered by mechanical guarantee and made in the UK.