NEMIX RAM 4GB (1X4GB) DDR3 1066MHZ PC3-8500 MacBook Pro (Late 2006 - Late 2008) Pre-unibody iMac (Early & Mid 2009) iMac (Late 2009) MacBook Pro (Late 2008-2010) Compatible Memory at Amazon.com
DDR3 RAM for Late 2009 iMac | MacRumors Forums
Timetec 16GB KIT(4x4GB) Compatible for Apple DDR3 1067MHz / 1066MHz PC3-8500 CL7 Dual Rank for iMac (Late 2009 21.5-inch / 27-inch) SODIMM Memory MAC RAM Upgrade for iMac 10,1 and iMac 11,1 at Amazon.com
Apple iMac 27-inch late 2009| i7 2.8Ghz | 16GB Ram | 500GB SSD | HD 4850 | eBay
Catalina 10.15.3 running decent on my mid 2009 iMac. Gonna max out the RAM to 8GB. 🤗 : r/CatalinaPatcher