I have branched your comment to a new thread in the Solid State Drives Community, since the issue was different from the original topic of the thread.
The model numbers SSDPEDMW400G4X1 and SSDPEDMW400G4R5 are both for the Intel® SSD 750 Series 400GB, 1/2 Height PCIe 3.0 Add-in-card.
The difference in the last two digits, X1 vs R5, is for the original packaging from factory. SSDPEDMW400G4X1 is a single pack and the SSDPEDMW400G4R5 is the reseller 5 pack. Retailers normally sell any of the two model numbers individually, but the SSD itself will have the same size and form factor.