This latching relay board is multi functional.

It can be triggered by either a single pushbutton switch or +ve pulse input to latch and unlatch relay,

or by using two pushbutton switches or +ve inputs, one to latch, the other to unlatch the relay.

single input to latch and unlatch relay

wire a permanent supply to the board.

select option link 1 on board.

wire the pushbutton switch or +ve pulse into the input terminals.

with each input, the relay will toggle on and off . 

If the permanent supply is removed the relay will default to off (unlatched) state.

two inputs to latch and unlatch the relay.

wire a permanent supply to the board.

select option link 2 on board.

With each switch or +ve pulse into the input terminals, the relay will latch.

With each switch or +ve pulse into the reset terminals, the relay will unlatch. 

If the permanent supply is removed the relay will default to off (unlatched) state.