Early in the 18th century, Bristol, with companies such as R. & W. King (one of the companies later incorporated into the United African Company), and then Birmingham, became the most significant European brass manufacturing city. It is likely that most types of brass manillas were made there, including the "middle period" Nkobnkob-Onoudu whose weight apparently decreased over time, and the still lighter "late period" types such as Okpoho (from the Efik word for brass) and those salvaged from the "Duoro" wreck of 1843. Among the late period types, specimen weights overlap type distinctions suggesting contemporary manufacture rather than a progression of types. The Popos, whose weight distribution places them at the transition point between Nkobnkob and Onoudu, were made in Nantes, France, possibly Birmingham as well and were too small to be worn. They are wider than the Birmingham types and have a gradual, rather than sudden, flare to the ends.