Spectrum’s ThunderBolt portable lightning detector has a storm and lightning detection range of 75 miles (120 km in metric version) and a detection frequency of 10 kHz. Warning modes include text messages via a 2-by-16 LCD screen, red LED warning light and an audible tone. It automatically displays ranging, storm approach speed, ETA at user location, time to clear and sever storm/squall line detection. It measures 6.4-by-3.4-by-1.5 in. and weighs 14 oz.