Wixey WR365 Digital Angle Gauge and Level Flip-up display for easy viewing from any position Built-in level display using Dead Level Technology TM is always visible and permanently stored. HOLD feature allows you take a reading and hold the value while you move the gauge to a new position. The machined aluminum base imbedded with high strength magnets sits perfectly flat for optimum accuracy. It also has a built in V groove for use on pipes or conduit. AAA batteries for super long life