These half-Heusler compounds are also semi-metals, with low carrier densities and non-trivial topological features. The crystal structures are also non-centrosymmetric, which is interesting from a superconductivity point of view, as one expects an admixture of conventional spin singlet and unconventional spin triplet pairing states. Additionally, the isostructural Er compound develops a magnetically ordered phase in the region of superconductivity. It is not known if the ordering is anti-ferromagnetic, or a more exotic spin spiral state. It is also unknown to what extent the magnetism plays a role with the superconductivity. Muon spin rotation and relaxation is an excellent tool for studying systems such as this, and in this proposal we suggest a thorough investigation of the flux line lattice using transverse field uSR. We will also search for spin triplet pairing in zero field.