This pack of 5 MEDITE Premier MDF boards are cut to a more manageable size of 400mm x 400mm each. The 3mm thick MDF fibreboard has a smooth surface face and a uniform fibre structure. Due to these properties and the fact that it is a very thin MDF panel, it makes an ideal choice for use with laser machines for cutting and engraving. MDF can be used for a variety of DIY and crafting applications. Medium Density Fibreboard (MDF) is a reconstituted wood panel product. Measurements (length x Width): 400mm x 400mm 40cm x 40cm 15.75 inch x 15.75 inch Medite Premier MDF conforms to E1 formaldehyde levels, as well as complying with the lower levels required by CARB phase 2 (CARB Phase 2 compliant <0.11ppm). As a natural timber product, and as this is a very thin MDF board, there could be a slight bow or twist when placed on a flat surface. This is normal and it is recommended that the edges are taped down when used for laser machining applications. There is a small tolerance in thickness of +/-0.15mm.