20% off jeans at Barneys Co-Op

I don't know the details of this, but I saw an ad in Elle about it.

If you bring in a pair of jeans to Barneys Co-op (they'll be used to make special Loomstate jeans) you'll get 20% off a new pair.

Does anyone know more details about this? I'm wondering (since they're going to be used not donated) if they have to be premium denim?