I purchased the Castelli Venti Socks on sale for my winter riding here in Nor-Cal. The socks have done a great job keeping my feet warm in morning rides 37 to 45 F. The toe box area is built up a bit more than the rest of the sock providing a thicker barrier against the cold. The socks are the typical Castelli size being small for the U.S. market, I am a size 9.5 in U.S. shoe sizes and I ordered the XXL which fits well however could be a bit larger.
Good socks, seem to hold up well to washing being careful that these do not end up in the close dryer.
Overall good socks and I got them at a great price at BTD.
These socks fall are generally comparable to Woolie Boolies Woolerators and are not quite as warm as my non-branded alpaca socks. I like the height compared to the aforementioned name brands. I have not had them long enough to comment on durability, but so far so good.