Primelok Shadowood Smooth board has a smooth flat surface finish. The top of the board begins with a 20mm smooth surface, a platform for where the following board will be placed. Following, is a 40mm wide groove. The groove begins rather deep at 5mm. Gradually, as the groove progresses, the depth decreases, eventually meeting with the smooth surface. When the next board is fixed, the Shadowood profile provides an intense shadow line.