With drop forged steel frame, micro-lapped tungsten carbide tipped measuring faces and constant force ratchet.
Parallelism: (2+L/100)mm (fraction rounded down).
Counter to 0.01mm (.001").
Vernier scale graduated to 0.001mm (.0001").
L = maximum measuring length.
Accuracy: Flatness: 0.6µm for up to 300mm.