Hydrophilic stone wool with a thickness of 25 mm and a density of 75 kg/m³, meaning the boards are rigid and do not compress under the weight of the overlying vegetation. However, the boards are not designed to withstand pedestrian loads. The boards can be used to create water reservoirs. The Greenfix substrate board is typically used beneath planting beds with shrubs, perennials or small trees, or in vertical green wall systems. Stone wool is non-combustible. In the event of fire, it produces only limited smoke and no toxic gases. Stone wool is also fully recyclable.