Alarm switch has the self-holding type reed switch. That is, when the N pole of magnet float is coming near, the switch with be closed (on). After the magnet float passed by, the switch still remain closed (on). And when the magnet is coming back, the switch will be open (off) again. And after the magnet passed away, the switch still remain open (off) also. When the switch is installed upside down, the on-off operation of above will be revised. Therefore, the operation (on-off) is easy to change on the side.
As our switch has no polarization, it makes no problem in electric circuit whether wires are connected with terminal 1or 2