Very often for safety reasons, to reduce the risk of slipping. Holes provide ‘drainage’ for liquid spillage, and capture debris in swarf-prone areas. Dry dust and debris can also be a slip hazard as they act like marbles on the floor surface. If debris falls ‘through’ the mat, then this risk is minimised. Matting with holes should be cleaned regularly to ensure the holes do not clog up, giving the mat optimum slip-resistance performance.