is the density-of-states e↵ective mass, which can also be expressed in terms of the band e↵ective mass m ⇤ b and the valley degeneracy N V . The weighted mobility is a material property that encodes the electronic structure and scattering mechanism and, therefore, it succinctly quantifies the electronic transport properties of materials. In a two-band model, the transport coe cients in Eq. ( ) must be revised to account for the e↵ects of the second band. Transport models accounting for multiple valence (or conduction) bands, where transport is assumed to be dominated by a single charge carrier type, have shown that high TE performance is achieved by increasing the valley degeneracy in many cases. Here, we demonstrate that TE transport in narrow-gap semiconductors and semimetals, where both electrons and holes are present in comparable concentrations, depend on the asymmetry of the electron and hole transport properties; in other words, we consider isotropic conduction and valence bands with di↵erent e↵ective masses and scattering times.