Since their discovery and study by the end of the last millenium, string dualities have proven to be an invaluable tool in the understanding of different regions of the string parameter space. The Swampland Distance Conjecture predicts the appereance of light towers of states when proving infinite distance limits, which in turn can be understood as new d.o.f. arising from the new perturbative description. While for high number of spacetime dimensions and supersymmetry the possible arrangement of towers and duality frames is quite constrained, as we go down in dimensions and supercharges this becomes more complicated. In 4d N=1 theories the existence of ½-BPS EFT string solutions might impose extra constrains in the arrangement of light towers and perturbative duality frames. We show how the tension of these EFT strings, which can be directly read-off from EFT data, determines the arrangement of light towers and duality frames in a unique way, without the need of knowing the precise string construction from which the EFT results.