Made of plain, unplated brass. The brass will darken as it ages.
At a glance the C9b ukulele capo looks like the Shubb model 5 (banjo) capo, but it closes onto a smaller neck, and accommodates a slightly wider fretboard. Testing on many brands confirms this capo is a perfect fit on all tenors, sopranos, concerts, and baritones …except the occasional baritone with a very large neck. In these cases, the banjo capo (any model 5) is a good fit.
If you prefer the feel of a brass capo over the lighter weight aluminium on your ukulele, then this is the capo for you!