From the trusted Australian brand, Tradco Hardware, these window locks are made of solid stainless steel with a hand aged brass finish. They connect the window and the window sill with an arm that retracts when the window is closed. To open, use the key to release the pin and then push the window to one of the twelve intervals and lock the arm to secure it.
If you have a number of casement windows, each with a stay, you can choose to have them keyed alike for consistency, or differently for an added security feature by making a note in the comments when you check out. When installed with an antique brass casement fastener - which pulls the window flush with the frame - they create the ideal window hardware configuration.