  In this talk we study the low-energy effective couplings generated by
strongly-coupled electroweak models that contain heavy composite resonances.
Invariance under $SU(2)_L\times SU(2)_R$ is a key ingredient in the
construction of the resonance action. For simplicity, in these proceedings we
focus our attention on the impact of a heavy colourless vector V, which
transforms as a triplet under the custodial group. More precisely, we study the
couplings that are relevant for the vector form-factors of the L+R current into
two electroweak Goldstones and into two Standard Model fermions, which
contribute to the oblique parameters S and T and the anomalous $Z\to f\bar{f}$
couplings, respectively. Our predictions are compatible with bounds from direct
and indirect searches for Mv > 1.5 TeV. Finally, although we consider an
antisymmetric tensor formalism to describe the vector resonance, we derive the
equivalent action in the Proca four-vector representation and show that the
predictions for low-energy couplings and form-factors are identical, as
expected.
