The NF-Series of packless silencers are effective from 31.5 Hz to 8,000 Hz, and is specifically engineered for maximum noise reduction from 125 Hz to 2,000 Hz and achieves peak performance in the 500 Hz octave band. Four models are available: NF95, NF75, NF55, and NF35, in three lengths: 36 in., 72 in., and 108 in. The units are suited for hospitals, cleanrooms, or other critical environments where fibers in the airstream can't be tolerated.