Housing Caps - (brake and derailer) Brass
Brake and derailleur housings are usually capped with ferrules. Normal ferrules (or "caps"!) are brass underneath chrome-plating. The purpose of the chrome is to make them look shiny, but it's an unnecessary step. Ours are unplated, so what you see (brass) is whatcha get. They dull with age and exposure, as brass does. Oddly, unplated brass caps cost MUCH more than plated ones, but they are groovier. We use them on all of the bikes we assemble, and you can get them too, here, from us, as long as we have them. Made in Colorado, the brass-cap capitol of the West.
Brake housings take 5mm caps, derailer housings take 4mm. You get six of each.