This is a genuine Black and Decker replacement part,it is sold individually.
This is the part of the String Trimmer that contains the cutting line.
This part includes the spool and cutting line for the models shown below.
This is a dual line spool.
The cutting line is .065 gauge.
It is replaced by removing the spool cover and placing it inside the spool housing, then feed some line through the spool housing and replace the spool cap.