This is a hand-dyed, wool/nylon blend thread. The nylon adds strength to the thread so that you can work with longer strands. The thread is fuzzy, like wool, so it will blend in at the edge of your wool applique pieces. This thread feels very similar to Aurifil's wool thread.
Prescencia perle cotton is not fuzzy, and it has a much tighter twist. Even though it does not have a sheen, it will be more visible at the edge of your wool applique shapes. Choose the kind of thread for the look you want.
The makers of both threads promise that their threads are colorfast and I have no reason to doubt them.
Click here to see a video about larger needles, thicker threads, and needle threaders.