Modern hard disks achieve higher density through less challenging mechanical requirements: they are sealed, in some cases filled with helium, platters can be ve

Modern hard disks achieve higher density through less challenging mechanical requirements: they are sealed, in some cases filled with helium, platters can be very thick and very stiff, heads can be fixed instead of being lowered towards the disk when it is inserted, and for these and other reasons heads can get much closer to the platters and achieve miniaturization levels that are not possible with removable media.