Sash fasteners are an old fashioned type of lock fitted at the midrail of sash windows over the join between top and bottom sash. To satisfy insurance requirements some have a key operated lock incorporated into their design, otherwise a separate specialist window lock should also be used.
Brighton fasteners have a threaded arm which is lifted over the join and secured by screwing down a bell-shaped nut to give a sturdy fit on all sash windows. The best choice for loose fitting windows.
Swing and Quadrant fasteners have a sprung hinged arm which is swung 90° over the join to prevent movement. These are the most traditional pattern of sash window fastener.
Claw and Fitch fasteners are rotated 180° to release or fasten the two sashes. Often the only option for narrow midrails such as on double glazed or old Georgian windows.