My suggestion if you have not done so already is go to You Tube & search "replace or install SSD in iMac" for detailed instructions. I have replaced an SSD and the HD's as well & you will need to buy a tool kit. It includes the right screw drivers & suction cups to do it right. Best Buy may sell them on-line but google "replace SSD on a Mac" & go from there. It's not for the unskilled but it can be done.