Delicas are very tiny sliced tubes, and are somewhat like working with blocks, instead of balls.  
In older pattern books, instructions tell you to use Delica Beads.    Because there are so many brands of similar beads today, 
newer pattern books tell you to use Cylinder Beads, which is a generic term.

SIZE 8/0 LARGE

8/0 Delicas are approx. 3.3mm in size.   They are sold in 10 gram tubes. There are approximately 330 8/0 delicas in a 10 gram tube.