For use with 1, 2 or 3-Hour-Rated Floor-Ceiling and Roof-Ceiling Designs, UL Classified UL555C, Meets or exceeds NFPA-90A, UL/cUL Listed for use in the following Floor Ceiling and Roof Ceiling Assemblies: L521, L528, L546, L558, L562, L574, L576, L581, L583, L585, P522, P533, P538, P545, and P547 when installed per instructions, Stainless steel closure springs