Designed to fit to the frame/box and restrict movement of the sash window. Sold in sets of four (enough for two windows if not used in a night-vent configuration). The secure stop is non-load bearing and therefore is not subject to the requirements of BS EN 14351-1. Ideal for adding extra security to upper floors, particularly for homes with children, these lockable stops are insurance compliant. Insert Diameter: 10mm Stop Projection: 19mm Strike Plate: 26mm x 19mm x 2mm