1TB SSD Pcie MZ-KPU1T0T/0A6, SM1024F for Apple iMac 21.5-inch A1418 Retina(Late 2013 – Late 2015), iMac 27-inch A1419 Retina(Late 2013 – Late 2015), Mac mini (Late 2014), Mac Pro (Late 2013), MacBook
How to Install a PCIe SSD in a 27-inch iMac (Late 2013)
NVME 512GB SSD For Apple iMac 21.5 A1418 EMC 2638 Late 2013 3 Years Warranty | eBay
Upgrading an older iMac's PCIe SSD: Third-party solutions that save you beaucoup bucks | Macworld
Timetec 256GB MAC SSD NVMe PCIe Gen3x4 3D NAND TLC Read Up to 1,950MB/s Compatible with Apple MacBook Air (2013-2015, 2017), MacBook Pro (2013-2015), iMac (2013-2019), Mac Pro (2013), Mac Mini (2014) at Amazon.com