... to use and maintain. 1. IntroductionPortable Area Tester is a professional area testing instrument which adopts GPS Positioning System. ... like farmland, green land, forest, factories and mines, water area, mudflat,etc. 2. Characteristic·Advanced function, rapid survey.·English ... measurement range: 0-300 acre .Precision:3% measuring area>0.5acre The bigger,the more accurateDistance measurement range: ...