%0 Journal Article %T On Graev type ultra-metrics %A Menachem Shlossberg %J Mathematics %D 2014 %I arXiv %X We study Graev ultra-metrics which were introduced by Gao. We show that the free non-archimedean balanced topological group defined over an ultra-metric space is metrizable by a Graev ultra-metric. We prove that the Graev ultra-metric has a maximal property. Using this property, among others, we show that the Graev ultra-metric associated with an ultra-metric space $(X,d)$ with diameter$\leq 1$ coincides with the ultra-metric $\hat{d}$ of Savchenko and Zarichnyi. %U http://arxiv.org/abs/1405.2244v1