6300F23S - Steel Perforated Diffuser - F23 Lay-In - SupplyKrueger 6300F23S Steel Perforated Diffuser F23 Lay In Supply The 6300 series features modular air pattern controllers mounted to the backside of the perforated face and a molded fiberglass backpan prescored for spin in collars (not included) to help meet the stocking requirements independent of round duct connection size. The 6300 series exhibit typical isothermal throws of 10 to 13 for 4 way air distribution and 21 to 27 for 1 way air distribution.