This is a late 2013 21.5-inch iMac. The HDD has been replaced with a 2TB SSD, resulting in faster boot times. I am selling it because I have upgraded to a new Mac. It can be used without any problems for web browsing and GarageBand, etc. Since I transferred the keyboard and mouse to my new Mac, I will include a wired USB third-party keyboard and mouse for startup. The marks on the back are from double-sided tape. - Model: iMac - Storage: 2 TB SATA drive - Memory: 16 GB DDR3 - Included: Keyboard, Mouse Please understand that this is a used item and no claims or returns will be accepted. Thank you for looking.