It fits the Randonneur rack, Rando rack with decaleur, Pass Hunter rack, Pass Hunter rack with decaleur, and Constructeur front rack. Attachment is with the four, included, 5mm screws.
We suggest using a bungie cord or cargo net to secure your cargo in this, or any, basket-type rack. It wouldn't do to launch a precious microbrew when you hit a big bump.
More photos can be found in this previous blog post.