N - Brand New (10/10) Completely brand new, straight from the source
S - Unused (9.9/10) Completely unused. This may mean it was purchased by the owner; but has been kept unused for a certain period of time.
SA - Very Good Condition (9.8/10) Almost new. This refers to items that are good as new. They may have been used a few times and may have very minor flaws
A - Good Condition (9.5/10) These are slightly used items with few scratches and marks
AB - Good Condition (9/10) Almost new. This refers to items that are good as new. They may have been used a few times and may have very minor surface scratches or marks, just slightly below A condition
B - Used (8/10) These are fairly used items with some scratches and or marks
C - Used (below 8/10) These are fairly used items with obvious wear and tear