I want to add a PCIe flash hard drive to an iMac 21.5", late 2013. I have a hard time locating such a part. OWC has none, and some of local Mac dealers were clueless to what I'm looking for. If you know of a specific part number, and where to order from, please post here. I've replaced the Hitachi hard drive with an Intel 530 SSD. Works fine. During memory upgrade, I noticed the empty PCIe slot on the logic board. Would be cool to put in in service, too. For easy access to internals, I've used some black electric tape to keep the display in place. Doesn't bother me!