I am using the smaller size of these levers, and strangely when I switched from aluminium to steel bars the lever that fit into the former was too small for the latter (even though both bars had the same clamp size and I would have thought as a result the same internal diameter). Sorry that doesn't really answer your question, but all I can conclude from that and from I read elsewhere it seems that there can be small variations between the internal diameters of bars, even of the same style. But I am not an expert...
I am using the smaller size of these levers, and strangely when I switched from aluminium to steel bars the lever that fit into the former was too small for the latter (even though both bars had the same clamp size and I would have thought as a result the same internal diameter). Sorry that doesn't really answer your question, but all I can conclude from that and from I read elsewhere it seems that there can be small variations between the internal diameters of bars, even of the same style. But I am not an expert...