The ROADrule CEVNI is a quick reference tool that identifies navigation aids and markers as prescribed by the European Code for Inland Waterways. It takes a large amount of complex information and makes it easy to understand using a sliderule design with a magnifying lens.- Identifies navigation aids & markers as prescribed by the European Code for - Inland Waterways- Displays 38 Navigation Aid Definitions- Displays 12 Rules of the Road- Magnifying lens for clear readability of definitions- Durable plastic construction- Lifetime warranty