OBV & OBVA window restrictors

Restrictors for Timber, PVCu and Aluminium Windows

Automatically restricts window openings regardless of sequence of operation.

OBV for PVCu & Timber

The Winkhaus OBV & OBVA (grub screw) are a family of window restrictors, which are designed to help prevent small children opening windows fully and falling our. The restrictor automatically restricts the opening of window greater than 50mm-100mm.  It also prevents windows from slamming shut.  Restrictors are surface mounted vertically or horizontally on both outward and inward opening windows, and can be easily retrofitted to existing windows as an additional security and safety device.

OBV for Aluminium Windows

Winkhaus have purposely designed and developed an adaptor to enable the fitting of OBVs to aluminium casement and tilt-turn windows.  A choice of fixing holes provides the most suitable screw positions depending on profile design.  Winkhaus can supply purpose made jigs to ensure accurate and consistent drilling of fixing holes.


  • Restricts the opening distance in the turn position to apprx 50mm if mounted on the lock side, when mounted horizontally variable opening distances can be achieved
  • The OBV locking bar can be released for full operation of the sash by keeping the push button depressed
  • Automatic locking; when the window is closed from the turn position the limit opening function re-engages
  • Prevents windows from slamming shut
  • Can be retrofitted to existing windows as an additional security and safety device
  • Easily fitted using 5 screw. The steel hook is fixed with three screws.
  • Maintenance friendly as frame section can be adjusted within a range of +3mm


  • Extensive range of angle packers available to allow fitting to PVCu windows
  • Suitable for Casement & Tilt-Turn Aluminium Windows
  • Available in White, Brown and Mill Finish for self coating


  • Conforms to BS6375 part 2: Load bearing capability of Safety Devices


A full fitting guide is available within the download section