The Winkhaus OBVA Safety Catch is one of the family of Window restrictors which are designed to help prevent children opening windows fully and falling out, and windows from slamming shut. The OBV locking bar can be released for full opening of the sash by keeping the push button depressed.
The safety catch automatically restricts window opening regardless of the sequence of operation, and locks automatically. When the window is closed from the turn position, the limit opening function re-engages. This product is maintenance friendly as the frame section is adjustable within a range of 3mm.