The Expedition 15TDCL has a sighting hole in the mirror for the most accurate bearings, silicon rubber feet for best friction on map when taking bearings and is equipped with Romer scales for plotting positions on maps and mm/inch map measuring scales.
Built-in magnifying lens and luminous markings for night navigation are other important features for the most demanding users.
The Expedition 15TDCL also has magnetic declination adjuster as well as a built-in clinometer for measuring vertical angles.