Abstract: A spring-loaded quick-release mechanism to a locking security grille is triggered by (i) manual activation, preferably through a foot switch, or (ii) fire, typically through a thermal fuse. Fins incorporated in, and/or affixed to the bars of, a security grille are preferably rotating, normally in phase, so as to serve as a louver or, when completely closed, an interlocked security shield, or panel. One locking release mechanism, which may optionally be quick release, has a sliding bar with alternate (i) extension and (ii) notch regions that respective engage the ends of solid, purely cylindrical, elongate prisms, normally cylindrical bars, to respective lock, and disengage, these prisms in a security grille. Finally, a security grille with standard universal retention assemblies variously serves to retain any, and any combinations, of tubular bars, solid bars, fins mounted to bars, and solid fins.