In a recent paper Silver and his collaborators concluded that the extended state electron mobility micro c in amorphous silicon was about 500 cm 2V -1s -1. The calculations leading to this value were based on the multi-trapping transport model, the experimental drift mobility value of μ e = 1 cm 2 V -1 s -1, the tail state distribution suggested by field effect data and an assumed thermalisation depth of the electrons of 0.29eV. In the following it will be shown from experimental results that the above thermalisation depth is fundamentally inconsistent with the observations and, when used with the measured micro e, leads to unrealistically high calculated micro c -values. We also show that with a thermalisation depth appropriate to the conditions under which micro e is determined, the experimental results and the computed micro c-values (10 - 20 cm 2 V -1 s -1) form a consistent picture.