The B174 Fan is no longer available. This is significant because the new B1011-F fan cannot be used instead of a B174 fan. If your B174 fan has failed please contact ETC Technical services to talk about options for retrofitting your SmartPack to work with the new fan.
New Style Smartpack Fan Part number B1011-F (note that photo labels have a typo).
Old Style SmartPack Fan, part number B174 - NO LONGER AVAILABLE