The 51100 series architectural, perforated diffusers use curved blade-type pattern deflectors mounted in the neck and are available in preselected 1, 2, 3, or 4-way discharge air patterns. Individually adjustable curved blades allow field adjustment of the air pattern in each direction, which may be field set to any position between a vertical throw and a tight ceiling, long horizontal throw pattern. The pattern deflectors in the neck create aspiration of secondary air through the perforated face where it is mixed with primary air then discharged through the perforated face. This aspiration and mixing effect reduces the discharge air temperature to avoid cold air drafts. Additionally, it removes smudging material from the secondary air by impingement on the perforated face. Ceiling smudging of adjacent, hard to clean ceiling surfaces is greatly reduced. The 51100 series diffusers exhibit typical isothermal throws of 10’ to 18’ for 4-way air distribution and 21’ to 35’ for 1-way air distribution making this diffuser an excellent choice for irregular room shapes. Matching returns are the 1190 and 51190 series.