PLACOM Roller-Type Digital Planimeters Offered in a roller-type model this planimeter features a unique 6-digit pulse count operation that permits cumulative measurement of areas up to 10m-100 times the measuring capacity of ordinary planimeters. Enhanced with advanced micro-processors for accuracy, this instrument is ideal for many applications where precise large area measurements are needed, such as in civil engineering, surveying, forest management, mapmaking and agriculture. Other features include hold and measuring control, clear liquid crystal digital readout, and scale readings in either Metric or English. Comes packaged in a plastic carrying case with AC adapter ( battery included) and operating instructions. Features easy roller operation ï ¿ ½ simply follow the outline of the area to be measured, the reading on the digital display corresponds to the circumscribed area. Please note: No. KP90N has a computing function that gives the measurement readout in the scale desired ( sq.ft., acres, etc.) . Specifications: Max. measuring range: 325mm vertical; 30m horizontal Accuracy: within ï ¿ ½ 0.2% ( within ï ¿ ½ 2/ 1000 pulses)