Fitted to the sash to restrict the opening for security & safety reasons etc. or fitted to allow the sash to be opened to allow ventilation without compromising on security Can be fitted to the frame/box and prevents the sash being opened beyond that point. Ideal for windows an upper floors where children can be left unattended and offers that extra bit of security and peace of mind. Drill the barrel into sash frame and fit the strike plate to the sash to prevent any damage. Supplied as a pair. Finished in Polished Brass - for more information see the finishes guide here.