I was a little heart broken when my quilt came back from the longarmer. Dark threads could be seen trapped behind the pale yellow backing fabric. Then this little tool came along and I crossed my fingers it worked as the YouTube video showed. Well, voila! Best $12 I’ve spent in ages. It glided through the back layer to grab those dark threads and pulled them free without damaging the the fabric.
The only thing I found was that it would sometimes snag a few cotton batting fibres as well. But I just sniped them flush with the backing.