The clutches listed here are brand new but have been returned due to being damaged in transit to the initial customer. They have been fully inspected and the damage has been limited to broken or bent fins. The clutches split in the middle so there are two halves to the fin, an upper and a lower. So it's not uncommon for a clutch to be missing half of a fin or even a quarter of a fin if one corner is nicked.
The rating is based on a total loss of fin by visual inspection. The damage could be in one or more locations and is to be used as a reference in gauging any loss of ability.
Attached is a picture showing what a typical -1/2 fin rating would be.