Those Disk Drives are not the original Amstrad standard.
Yet they were far more cheap and are nowadays easier to use.
Especially the 3½" (3"1/2 ?) as those disk are still availlable in some retailers. You can also easily find such drives in any garbage if you properly scavenge old rusty computers.
Many Modern CPC users replace their old 3" by an external 3"1/2, adding a Disk drive A-B / B-A switcher.
Also a side switcher allows to use a 3"1/2 disk like a 3" disk...switching manually the sides (yet a decent sofware can do it).
Softwares released on 3"1/2 disk
This pure awsomness even use a full DD disk with 720Ko, yet you have to get a DD disk Drive.