System letterbox Potsdam 877 Spacious system letterbox Potsdam 877 in landscape format with front insertion up to max. format DIN C4. The Potsdam 877 letterbox is particularly suitable for wall mounting and can be extended as required with additional boxes (in a horizontal or vertical arrangement). Unevenness on the wall can be levelled out with rubber buffers (included in the scope of delivery). The sheet steel material used is highly weather-resistant and the colour-fast paint finish is characterised by both UV resistance and scratch resistance.