2-wire connection (neutral conductor not required). Neutral conductor optionally connectable (recommended for the connection of low loads < 10 W/VA). For switching lighting systems. Operation in 1gang 2way installations via push button input. Operation also possible via conventional push buttons (2020 US-500). Without control unit. For control element flex, 1gang, 64711-500. For control element flex, 1gang, wireless, 62711-WL-500. For control element flex, 2gang, 64721-500. For control element flex, 2gang, wireless, 62721-WL-500. For ABB Comfort switch flex control element 64765-…-500. For ABB Watchdog 180 flex sensors 6476x-…-500. For ABB Watchdog 180 flex sensors, wireless, 6276x-...-WL-500. For ABB presence detector flex sensors 6475x-…-500. Combinable with extension insert, 64891 U-500. The use of dimmable LEDi is required. 64814 U-500