Patent ID: 7121500

Claim:
A stackable winding comprising: an inner paperboard tube having a radially outer surface and a radially inner surface; an outer paperboard tube having a radially outer surface and a radially inner surface; the inner paperboard tube being coaxially disposed within the outer paperboard tube such that the radially outer surface of the inner paperboard tube forms an interface with the radially inner surface of the outer paperboard tube; the interface being devoid of adhesive and the inner paperboard tube being axially offset with respect to the outer paperboard tube such that one end of the inner paperboard tube projects beyond the outer paperboard tube and forms a male end of the core and an opposite end of the outer paperboard tube projects beyond the inner paperboard tube and forms a female end of the core, and further comprising a fastener that affixes the outer paperboard tube and the inner paperboard tube together to prevent relative movement therebetween, the male end of one core being insertable into the female end of another core for stacking the cores end-to-end.