Before the pocket calculator, every engineer computed on a slide rule: logarithmic C, D, A, K and L scales engraved on a celluloid or bamboo body, read through a glass cursor and its single hairline. This system borrows that instrument's grammar — parallel scale bands, fine graduated ticks, a sliding register — and dresses it in Pickett's vivid Eye-Saver Yellow with crisp black engraving. It is precision made visible: nothing decorative, everything measured.