Pooleys NM-1 Scale Ruler

Convenient length (240mm x 38mm) for cockpit use. Outside edges respectively read 0–60nm in 1:500,000 and 0–30nm in 1:250,000. Centre scale converts between kilometres (km) from 0–110km in 1:500,000 and statute miles (sm) from 0–70sm in 1:500,000.