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




