The AcuRite Portable Lightning Detector provides reliable lightning alerts for cloud-to-ground, intra-cloud, and cloud-to-cloud lightning strikes within a 25 mile, 40 kilometer range. The lightning detector notifies you of lightning strikes in your area with an audible alert, flashing red LED light, and on-screen message. Keeps a running total of strikes and estimates distance to the storm-producing storm. An essential tool for education leaders, public safety, and on construction sites. The lightning strike detector also features enhanced interference rejection capabilities to help prevent false lightning notifications. Outdoor and indoor operation modes.