K&R Compact Alloy Curvimeter Map Measurer takes the hassle out of measuring distances on maps.

This double sided map measurer has black scaling on a clear white background and a large black hand for ease of reading on both faces . One of the faces converts to miles, whilst the other converts to kilometres. The articulated metal loop on the top of the curvimeter is ideal for attaching to map cases or sets of keys. 

Directions for use: Set the pointer to 0 by turning the small reset wheel on the base, then trace the route or distance on the map using the wheel as a guide.  The hand will then show the exact distance measured in proportion to the scale on the map.