Lie-Nielsen bodies are either solid cast Manganese Bronze or special Ductile Iron (the bronze is a bit heavier), and beautifully machined. The frogs and all mating surfaces are also fully machined and fully adjustable. The blades are hardened to a Rc 60-62. All blades are cryogenically treated A2 steel.
The No. 4 Lie-Nielsen planes are made in the form of Stanley's old bedrock" planes - which were the top-of-the-line tools until they went out of production about 50 years ago. The No. 4 is 9-1/2" long with a blade 2" wide.