This Peardrop Night Venting Fastener is easy to fit and allows the window to be open and let air in whilst remaining locked. i.e. It is night venting and can be locked in both the open and shut positions. This product is screw fitted and there is no need to fit trickle vents. The keep plate will screw to a mullion with a 20mm flat surface, leaving more room for mouldings. There is a nylon washer fitted behind the handle which is designed to reduce friction. Sold with key and fixing screws.