Redarc Chopper relays have two outputs which operate alternately with the application of inputs (+12V or +24V) from a single, momentary action, push-button switch.
CR1224 Whilst the button is pressed and for approximately ¼ second after release, one output supplies 12V or 24V (depending on supply voltage). Next time the button is pressed, the other output operates, in the same way.
CR1224L An output remains on (latched) until the next input signal causes the outputs to swap. The outputs are either +12V or +24V, depending on the supply voltage.