ISO 8503-4:2012 specifies the stylus instrument and describes the procedure for calibrating ISO surface profile comparators conforming to the requirements of ISO 8503-1. It is also applicable to the determination of the surface profile, within the range 20 μm to 200 μm, of essentially planar blast-cleaned steel. The determination can be carried out on a representative section of the blast-cleaned surface or, if direct observation of the surface is not feasible, on a replica of the surface.