Modular Series with choices of internal or external (sold separately) blower systems. Internal features 650 Max Blower CFM with ultra-quiet 0.8 Sones operation at normal setting, Choice of 13 different blowers to suit your installation (sold separately). Internal iQ6,P3, P5, P6 and P8 blowers -or external blower options for the ultimate in performance choices and quiet operation., Width: 30'', Depth: 22'', Infinite speed control gives you the convenience of automatically remembering last setting.