Metronomes typically include synchronized visual motion (e.g., swinging pendulum or blinking lights). Today the music division (part of Seiko Life Sports) produces metronomes and tuning devices. Metronomes will often include both BPM and tempo markings. Mechanical metronomes don't need a battery, but run from a spring-wound clockwork escapement. In another room he showed many metronomes were ticking at different speeds. Musicians practice playing to metronomes to develop and maintain a sense of timing and tempo. The 3 Travellers at Telefunken and Metronomes, and released three music singles. Two years earlier, Toshi Ichiyanagi wrote "Music for Electric Metronomes". In the 20th century, electronic metronomes and software metronomes were invented. Winners received walnut wood trophies that resembled metronomes. These include Metronomes, Happy Particles, Avast! Metronomes and beat counters are used to develop a sense of a steady pulse. She was originally in the group the Metronomes and married the lead singer, Alphonso Elliston. William Kentridge's "The Refusal of Time" (2012) features five metronomes in the video installation. Among the early bands to participate were Ebony Steelband and Metronomes Steelband.