Free abelian group of countable rank

Definition
This group, sometimes called the free abelian group of countable rank, is a free abelian group on a countably infinite generating set. Equivalently, it is the restricted external direct product of countably many copies of the group of integers.

It is to be contrasted with the Baer-Specker group, which is the unrestricted external direct product of countably many copies of the group of integers.