Digital ruler and protractor: A ruler with a digital protractor function that can measure length and angle at the same time. Say goodbye to complex measurement or tracking tasks. Metric and Imperial: Length measurement range 0-400 mm (2 rulers are 7 inches). The angle measurement range is 000.0 to 999.9, and the scale can be rotated more than 2 turns. Resolution 0.1; Accuracy 0.3. Zero any position (tare): Press and hold the small "Zero" button for one second, the value on the angle screen will reset to zero, and you can start measuring at any angle. The large knob in the center of rotation locks/unlocks the ruler at any angle, avoiding misaligned or lost measurement angles. SIMPLE BUT DURABLE: Simple in design, but made of stainless steel, this high-end material ensures excellent sturdiness. Over 2000 hours of coin cell battery life solves all battery life issues. Package contents: 1 Preciva Classic 200mm digital ruler; 1 CR2032 button battery; 1 user manual.