1.1 This specification applies to air ventilating grille units for detention areas, assembled in part from materials conforming to Specifications A627, A628, and A629.

1.2 The assemblies described herein are intended to provide two types of security, designated Type A and Type B.

1.2.1 Type A -A ventilation unit, utilizing homogeneous TR steel bars for the principal security component.

1.2.2 Type B -A ventilation unit utilizing perforated tool-resisting steel plate for the principal security component.

1.3 It is presumed that equipment manufacturers will fabricate and assemble the materials so as not to impair the performance characteristics specified in the applicable material specifications.

1.4 The descriptions herein of certain assemblies are not intended to infer that other assemblies cannot be used to obtain similar results.