This is a full sized railway sleeper scaled down to 4mm (OO). This model is intended for those building their own track from scratch or those who want a more realistic looking sleeper for detailing. These sleepers look great when printed with Wood PLA or painted with wood-colour paint. These sleepers will be longer and slightly wider than OO/HO scale sleepers. When you are trying to build a scene from a photograph, the OO scale sleepers often look a little too short (because they are). These sleepers are designed to get around that problem by providing a full sized version at OO scale.
If you are looking for replacement OO/HO sleepers look at T3D-001-000 and T3D-001-001.