Take the tool to the window and butt the square edges into the window recess, so that the arrows point horizontally away from the window. Pick the required overlap; 22mm (marked as a ‘recess fit’), 50mm, or 75mm. Keeping the tool in place, drill into thefitting surface using a 3mm bit through 2 of the 4 holes. It is recommended to use the top and bottom holes where possible
Watch a full video guide how to use this tool here.