The 6600 series perforated diffusers uses modular air pattern controllers mounted to the backside of the perforated face, which are factory set for 4-way air pattern. They are field adjustable for 1, 2, or 3-way pattern or may be removed for down blow without reducing the core area. The 6600 series diffusers exhibit typical isothermal throws of 12’ to 17’ for 4-way air distribution and 21’ to 30’ for 1-way air distribution. The modular capability makes the 6600 ideal for installations with changing air pattern requirements such as tenant lease spaces. Matching returns are the 6490 and 6690 series.