The E-layer is the thin layer that allows for more elasticity and damping of the mat and also determines the ball behavior. 'In earlier times, we already installed concrete for drainage', says Tijs van Lierop, project manager at Heijmans. 'The black E-layer comes atop of this innovative water-permeable concrete pavement. While the black carpet is filling the playing field, employees continuously measure the thickness: 17 mm. This construction is also used in all fields of the top clubs.'