Overrun

Garment manufacture is not an exact science and the exact quantity of say a dress that can be made with a specified number of bolts of fabric can only be estimated, not determined absolutely.  This is particularly true if you consider that allowance has to be made for rejects, see above, which are inherently unpredictable.

Therefore designers will have delivered to the factory more fabric that is absolutely required. If the factory manages to keep quality control tight then they may end up being able to produce more items than they have been contracted to do.

So for example if a blouse is expected to take a half meter of fabric to produce, with a 10% margin for error, and the brand has ordered 1000 then the factory will receive 0.5 x 1.1 x 1000 = 550 meters of fabric.  But say the factory has had a perfect run with no errors, then they would be able to actually make 1,100 blouses.

You might think that the factory would simply deliver the extra, but actually factories are in business too and they will hold back the extra and sell them separately.  Sometimes this will be done without the brand label, as the designer typically supplies the labels but only a limited quantity, but other times there are labels on these items.

It is garments like this which are considered Overrun and are of course the most desirable type of clothes from a outlet as they have no quality issues like Rejects but are merely excess to requirement of the factory.