Crucial Ballistix Sport 16GB Kit (8GBx2) DDR3 1866 (PC3-14900) 204-Pin SODIMM Memory BLS2K8G3N18A
http://www.amazon.com/gp/product/B00DSGLMSM?
I looked at my imac order and I read DDR3L. I'm not sure this ram with fit with the initial DDR3L. ( 2 x 4gb ddr3l + 2 x 8gb ddr3 )
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