Permit to manage the house Shutters opening, for example reduce the sun heat that's enter via windows. In Closed position it permit to improve the lockdown of your house Shutters. To install it, you just need to add standart Hook.To join the 2 part you need to use an iron wire. As it symetric, it can be mounted on Right or Left Shutter, Just fixing it using screws that's crossing the holes present in bottom part.