CMS 32GB (4X8GB) DDR3 10600 1333MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® iMac Core I7 3.4 27-Inch (Mid-2011) - C12 at Amazon.com
27" iMac Offers Easier RAM Upgrade
Timetec 32GB KIT(4x8GB) Compatible for Apple DDR3L 1600MHz PC3L-12800 CL11 for iMac (Mid 2011, Late 2012, Late 2013, Late 2014 Retina 5K, Mid 2015 Retina 5K) SODIMM Memory Module MAC RAM Upgrade at Amazon.com
Adamanta 16GB (2x8GB) Apple Memory Upgrade DDR3L 1600MHz SODIMM Compatible for iMac (Mid 2011, Late 2012, Early/Late 2013, Late 2014, Mid 2015), MacBook Pro (Early/Late 2011, Mid 2012), Mac Mini RAM at Amazon.com
Timetec Hynix IC DDR3L 1600MHz PC3L-12800 SODIMM Compatible with Apple 2011, 2012, 2013, 2014 MacBook Pro, iMac, Mac mini (16GB Kit(2x8GB)) Laptop Memory - Newegg.com
4GB PC10600 DDR3 1333MHz SO-DIMM Memory Compatible with 2011 MacBook Pro, Mid 2010/2011 21.5" & 27" iMac Models, 2011 Mac Mini (OWC1333DDR3S4GB) at Amazon.com
8GB RAM Upgrade for 2011 MacBook Pro & Mac Mini Core i5 & i7 – $34 | OSXDaily
Upgrade your iMac's RAM in less than 5 minutes - YouTube
27" iMac Offers Easier RAM Upgrade
timetec 32gb kit(4x8gb) compatible for apple ddr3l 1600mhz pc3l-12800 cl11 for imac (mid 2011, late 2012, late 2013, late 2014 retina 5k, mid 2015 retina 5k) sodimm memory module mac ram upgrade - Walmart.com
Memory RAM Upgrade for Apple iMac 21.5-inch Mid 2011 4GB/8GB DDR3 SODIMM | eBay