9edd1e4c_NTFS__Logical_Disk_Manager__Type_of_Container_
[Extend:] Because "N:" is already spanned, extending it will add another partition. [Add Mirror:] Adding a copy of "N:" will speed up time it takes to access and will provide a fault tolerance. The mirror could split across disks 2 and 3, or be put entirely on disk 4. [Type of Container:] 
Spanned
S i m p l e
S p a n n e d
S t r i p e
M i r r o r
S t r i p e w i t h p a r i t y
M i r r o r e d S t r i p e ( n o t s h o w n )
NTFS: Logical Disk Manager