iMac G5 2.0GHz 20" (M9845LL/A) 512mb 64x64 400MHz DDR SDRAM PC3200 184p DIMM 2.5v CL=3. Price for single unit most machines require this memory installed in pairs.For a kit Please buy and install 2pcs. Compatible Memory For iMac G5 2.0GHz 20" (M9845LL/A)