How to replace HDD/SSD in iMac Late 2009/Mid 2010/Mid 2011/Late 2011
Since I replaced the HDD of iMac (21.5-inch, Late 2009), I will explain the procedure at that time in detail with photos.
Models around this time are easy to disassemble, support OS up to 10.13 High Sierra, and hardware performance is not bad, so I recommend them.