This is the Motor Cooling Blower Fan and Shroud from Castle Creations.     
                                                                               
FEATURES: Fits motors with outside diameter between 1-1/2 and 1-7/8"           
            (38 - 47mm) such as the Castle Creations Neu-Castle 2200 and 2650  
          Plugs into receiver and drops motor temperature as much as 30°       
          One year limited warranty through manufacturer beginning at date of  
            purchase                                                           
                                                                               
INCLUDES: Fan with wire and connector, shroud and two zip ties                 
                                                                               
REQUIRES: Attaching to motor can and plugging into receiver                    
                                                                               
SPECS:    Length: 49mm                                                         
          Width:  44.5mm                                                       
          Height: 44.5mm                                                       
          Wire Length: (9.5")