As with the Vanguard, for the Redwood Hand Hammered Copper we are using a process of hand hammering the copper neck tube after it is formed. It serves several purposes: It hardens the metal, making it as strong and pull-down resistant as a brass neck and it also give the neck its specific tonal sound and response characteristics.
 
Sound characteristic:
Compared to the Redwood brass, the Hand Hammered Copper is a more complex sounding neck with the dominant core sound being slightly darker. There is a smooth brightness with warm undertones. Where the Redwood brass has a very straight and direct sound column, the Hand Hammered Copper is more complex and rich sounding.
 
-From kbsax.com