BRAND NEW FACTORY SEALED Kingston KTA-MB1066K2/8G 8GB Memory Kit for Apple iMac, MacBook Pro, MacBook, Mac Mini. Fits older units from 2009/2010. Apple part # is Apple MC016G/A. Please read below. 

2 4GB Modules Total 8GB. 1066 MHz, DDR3 SD RAM, SODIMM, 204 Pins, PC3-8500 SO-DIMM

This fits older units from early 2009 to mid 2010. Just this short select period of production. The iMac has 4 memory slots. Most of them only had used 2 slots with 2GB each. You can add these 2 and bring it up to 12GB. Max it will take is 16GB. MacBook Pro's only had 2 slots and most of them had either 2 1GB modules or 2 2 2GB modules. You can remove those 2 and put these in to get 8GB. At that time Apple charged several hundred dollars for a memory upgrade and they still do. 

You can go to support.apple. com and check your unit. Look under processor and memory and make sure it states 1066 MHz DDR3 SO-DIMM or DDR3 SD RAM. Below is a partial list that this should fit in. Please double check and verify.

MB Pro - 15" Mid 2010, 15" 2.53 GHz Mid 2009, 15" Mid 2009, 13" Mid 2010, 13" Mid 2009, 15" Late 2008 (Max 4GB) 17" (Early 2009, Mid 2009 and Mid 2010)

iMac - Early 2009, Mid 2009 and Late 2009.