Apple Computer , iMac 20-inch 2.66 GHz Core 2 Duo (E8135), Mac 21.5-inch 3.1 Ghz Core i3 (i3-2100), iMac 21.5-inch 2.5/2.7 GHz Core i5 (i5-2400S, i5-2500S), iMac 21.5-inch 2.8 GHz Core i7 (i7-2600S), Order Number, MC978LL/A, MC309LL/A, MB950LL/A, Model Number, A1311, Part Name, CPU Fan, Manufacture Part Number, N/A, EMC Number, EMC 2496, EMC 2428, EMC 2308, EEE Code, N/A, Compatible Apple Computer, iMac (21.5-inch, Late 2011), iMac (21.5-inch, Mid 2011), iMac (21.5-inch, Mid 2010), ,
Order you product here: 922-9385 CPU Fan for iMac 21.5 inch Mid 2010-Late 2011 A1311 MC978LL/A, MC309LL/A, MB950LL/A, 922-9385
source http://info.applepartsellers.com/922-9385-cpu-fan-for-imac-21-5-inch-2011-a1311-mc978ll-a-mc309ll-a-mc812ll-a-bto-cto