The scale is true (k=1) on the equator so that multiplying its length on a printed map by the inverse of the RF (or principal scale) gives the actual circumference of the Earth.
Skala yakti (k=1) ring equator kantos ngalihin lantangne saking peta sane kacetak antuk kebalikan saking RF (utawi skala utama) ngicenin keliling bumi sane sayaktine.