Abstract: An adjustable guard assembly constructed to permit quick removability when positioned in an enclosure, has a first and second section, each section including at least one transverse member, a plurality of longitudinally extending members which are secured at one respective end to an associated one of the transverse member. The two sections are mounted for relative axial movement with respect to each other so as to vary the width of the guard assembly and can be fixed at a given width by a resilient release mechanism which is operatively associated with the first section and the second section. The resilient release mechanism can be adjusted to provide a predetermined force necessary for maintaining the sections in their desired longitudinal position and to permit quick removal of the guard assembly from its assembled position in the enclosure when the predetermined force is overcome by any suitable means exerted against the guard assembly in an emergency situation.