Tales From My D&D Campaign Wiki

Colos cloaks are magical invisibility cloaks made by the Kua Toa. They are much cheaper to produce than regular magical invisibility items, but have the substantial downside of requiring skin secretions from a living KT, meaning that they cannot be used by other races. Of course, for the Deluvian Empire (a nation comprised of KT who would otherwise have to worry about the other races looting their cloaks in battle), this is actually an upside.