Easily work out distances and grid references with this handy map tool, or \'Romer\'. It\'s got a Romer tool plus scale rule for the OS Explorer 1 : 25 000 and OS Landranger 1: 50 000 scales, but it ill work for any map of the same scale (standard maps, custom made, OS Map prints, etc.) Use the rulers to quickly convert measurements on the map to distances on the ground, use the Romer squares to calculate six-figure grid references quickly and accurately. Find a downloadable PDF instruction sheet here. Get a Romer half price with any paper OS Explorer, Landranger, Road or Tour map