  We construct an action for NSNS 5-branes which is manifestly covariant under
O(d,d). This is done by doubling $d$ of the spacetime coordinates which appear
in the worldvolume action. By formulating the DBI part of the action in a
manner similar to a "gauged sigma model", only half the doubled coordinates
genuinely appear. Our approach allows one to describe the full T-duality orbit
of the IIB NS5 brane, the IIA KKM and their exotic relations in one formalism.
Furthermore, by using ideas from double field theory, our action can be said to
describe various aspects of non-geometric five-branes.
