0-728-02 Durite Relays And Flasher Units Durite 12V 25A latching changeover relay, Rated 25A at 12V DC, With resistor and without fixing bracket, 5 x 6.3mm Blade terminals, Sold in single packs, Latching relays (sometimes called keep, stay, fail-safe or impulse relays) are often used to make a circuit without the need to keep the coil energised, this has the ability to switch a circuit on and off or most commonly to switch power from one circuit to another, switching is achieved by using a single electrical pulse across the coil terminals 30 (12v +) and S (to switch/ground -) to energise the internal coil and is triggered by the use of a momentary on-off switch, the pulse pulls the coil in to switch the circuit from 56(+feed) and 56a(+feed) to 56(+feed) and 56b(+feed or not connected for off), once the momentary on switch is pressed again the coil is energised again and the circuit switches back to 56 and 56a, the latch relay is often used in energy saving applications because of it\'s minimal power drain on the batteries.