The 51400 series are square face, 4-cone, round neck ceiling diffusers and are available in a variety of frame styles to help meet the architectural requirements of today’s ceilings. The spacing of the inner cones in relation to the backpan result in a design possessing anti-smudge characteristics, preventing the buildup of particles on the ceiling, which is achieved by minimizing the low pressure region inherent to most 4-way directional blow diffusers. Also known as concentric cone diffusers, 51400s are constructed of one-piece stamped cones, which provide a clean, smooth appearance without mitered corner joints. The 51400 series is an excellent variable air volume diffuser as represented in its throw characteristics at lower airflows; at typical flow rates, isothermal throws of 9-16 feet make this diffuser ideal for mounting centrally in many spaces while providing high mixing rates in the space.