Closers or openers for wings, not otherwise provided for in this subclass spring-actuated {, e.g. for horizontally sliding wings } for swinging wings {, e.g. counterbalance with a coil spring perpendicular to the pivot axis }
Closers or openers for wings, not otherwise provided for in this subclass spring-actuated {, e.g. for horizontally sliding wings } for swinging wings {, e.g. counterbalance with a coil spring perpendicular to the pivot axis }