Home or stop signal. When the arm is 'off' or raised it incicates trains are clear to pass. When the arm is 'on' this indicates trains must stop at the signal. At night, Green and red lights inicate clear or danger to oncomming trains.This example is Box B inner circle home signal. Located on model railway layout, gauge 1, Lancashire & Yorkshire Railway Signalling School, built 1912, by L&YR and Bassett-Lowke Ltd, with associated equipment.