Fangrui Product Details Using This Digital Angle Protractor, You Can Measure The Angle Between Two , Not Only In Earth Direction. Angle Key At The First Face, And Then Rotate Slowly And Must Keep The Rotation To Another Testing Face, It Then Show The Angle Once You Not Move The Unit. Any Angle Measurement Is Using Gyro Technique. High Accuracy 0.05, High Resolution 0.01. Li- Battery Rechargeable, . High Resolution, Professional Measurement. Single And Dual , Convenient To Measure The Angle. Dual And Single With User Friendly Lcd Display Angle. V Shape Case For Easy To Fit At The Corner Or Pipe. With 5 Side Magnetic Base, Audible Alarming At Settable Angle Range, Any Angle Measurement. The Unit Could Be By Connecting The Usb Cable To The Unit And A Computers Usb Port. Accuracy: 0 To 20: (0.05) 20 To 70: (0.1) 70 To 90: (0.05) Measuring Range Single : 360,dual : 40 Resolution: 0.01 Response Time: Less Than 0.4 Second Zero Offset Drift Angle Per 0.0058(typical) Operating Temperature: