The premium No.4 bench plane has the base and frog cast as one piece to reduce chatter. The precision machined base is flat to 0.003 inch. It uses a 3 mm thick blade made from A2 steel for improved performance, along with a patented lateral adjustment feature and solid brass turn screws. The heavy, ductile cast iron body gives increased performance and is resistant to knocks or drops. For workshop, site or finishing of high quality work.