All thatis missing from a complete set is the larger sized porcelain "T6" spool.

These were reportedly used in southern regions of Italy in the early 1900s, when electrical requiremsnts were a lot less than these days.

From left to right, T5-S, T5, T6 and T6-bis. I don't know the porcelain versions' designations.

The T5 is CD 640, The T5-S is CD 650, the T-6 is CD 1076, not sure of T6-bis CD designation

I have ben assuming that early power distribution was 240VAC, 50Hz, 5 amps, perhaps lower voltages or even DC power were used in the early 20th century.

For a similar grouping, [id=83348684]