A romer is a specialist tool for measuring distances & working out grid references on a map. This romer supports both the OS Explorer 1: 25 000 & OS Landranger 1:50 000 scales, & can be used with standard maps, custom made & OS Maps prints. Use the rulers to quickly convert measurements on the map to distances on the ground, & user the romer squares to calculate six-figure grid references quickly & accurately. (get this as a printable PDF download) Half price offer on applies when no other offers or discounts are used. The discount is calculated in the checkout.