These are beautifully polished metal barrel beads.
8.25mm in length - 7.91mm wide outside diameter - hole is approx. 4.3mm
They were intended to be the match for the Chain Gang Patterns in Beaded Chain Mail Jewelry, but they are slightly too big. We cannot find the source of the original beads used in that book. These are the replacement from the same supplier. However, these do work with the pattern, as long as you only use 1 ring to connect, instead of doubling the rings like the pattern suggests. You can also use 16g rings with these larger beads!