It was conjectured by Davide Gaiotto, that K-theoretic Coulomb branches of 3d N=4 SUSY gauge theories possess structure of cluster varieties. In this talk, I will explain how to attack this conjecture in the case of quiver gauge theories. Time permitting, I will also present an application of our result to representation theory of quantum groups. This talk is based on a joint work with Gus Schrader, and is part II of Gus's talk.