There's a very nice review of the new Arca-Swiss Monoball Z1 ballhead on the-digital-picture.com:
For many years, the Arca-Swiss B1 Ballhead was the standard by which all other ballheads were judged. The Arca-Swiss Monoball Z1 Ballhead replaces this model and delivers the same performance in a smaller size and at a significantly lower price. There is not much to dislike about this change.
The reviewer compares it against the old standard, the Arca-Swiss B1 (which I have and love and review here on my website) as well as the Really Right Stuff BH-55.
