To activate simply twist the battery pack on the top of the Orange Flashing Whistle. The lit whistle will flash orange leds, this is the only light function. Each orange whistle comes with a orange lanyard. Dimensions: Length: 2.78 in. Width: .62 in. Lanyard: 36 in. LED Colors: Orange Orange Flashing Whistles include 3 replaceable AG13 Batteries.