Magnetic data of [Dy(C5H2tBu3-1,2,4)2][B(C6F5)4] in the crystalline phase, and at various concentrations as dichloromethane (DCM) and difluourobenzene (DFB) frozen solutions. These data are magnetic field sweeps at varying rates, that show steps at zero magnetic field. These steps are due to quantum tunnelling of the magnetisation. The sweep rate dependence of the size of the step allows us to quantify the tunnelling gap, and hence assess this metric as a function of phase and concentration.