This is a concealed door restrictor designed to restrict upvc doors. The larger silver part is designed to fix to the top of the door in the euro groove.The other small brass coloured part should be fixed to the top of the solid frame near the hinge side (See photo below for fitting Guide).
The restrictor has a friction screw on the plastic slider that can be tightened to increase friction as the door is opened and closed.
The restrictor will stop the door around the 90 degree angle and hold it in place against low to medium strength winds. A solid pull of the door releases it to close.
The item is unhanded. They are sold singly, the price is for one.