Portland PlotterMovable disc enables magnetic variation to be set on the instrument and a movable arm is divided into millimetres. With Captain Fields` protractor markings. Comfortably covers the largest Admiralty Chart with pencil guide holes give precision loction. Unique design ensures a truly parallel action and special ”slip and grip” gives ease of use. Manufactured from clear acrylic, 400mm in length.For more information or to enquire about Blundell Harling products, please email us at maritime@stanfords.co.uk .