3-In-1 Digital Angle Finder Provides Precision Measurements For Inside And Outside Angles, Lengths, And Calculates Simple Miter Cut Angles, Efficient Digital Miter Saw Protractor Function Calculates The Needed Saw Blade Angle To Cut Miter Joints With A Perfect Fit Every Time, Machined Ruler Edges Measure Inside And Outside Angles With An Accuracy Of +/- 0.2-Degree, Bright White Led Display Provides Easy Visibility In All Lighting Conditions, Durable, Rust Resistant Metallic Ruler With Deeply Etched Markings For Long Lasting Clear Readings, Powered By A Single Aaa Battery For An Extended Working Life Time, Compact Design That Is Easy To Store And Carry Around In Pockets, Wide Locking Knob Is Easy To Twist And Firmly Locks The Rulers In Place