Federleisten ( spring boards used in beds under the mattress to the the swinging feeling)> Thickness: 8 mm i.d.R.> With: 25-105 mm> common measurment: 53 mm> Length: 510 mm - 1370 mmm> Number of layers: 5 or 7> Thickness of each layer:> at 7 layers: 1,2 mm> with 5 layers: 1,6 mm>> Radius of the board: 3800 - 4000> surface: coating like sap of a tree> no coulouring> > Foil material: beech or birch