What you are looking at is the strings of 100 cool white LED lights that connect to one of the two adaptors
You can add up to 10 of these strings of 100 lights to the adaptor to create a string anywhere from 100 to 1000 lights. Each string of 100 lights is 10m long which is an easy length to wind through your Christmas tree.
These lights connect to either the straight line adaptor (so the lights run one after the other) or the "finger" style of adaptor so the strings all run off the central adaptor and look like fingers. The "finger" style is the easiest option when decorating your Christmas tree.
The video below shows how easy it is to string these connectable lights through your tree.