Shown here with the point safely inside
Shown here with the point ready for use.
See how it is tapered?
My aunt has one that is a little bigger (size 81) but immediately I grabbed it and asked why she had one. She uses it as a seam ripper. I, almost 30 years after graduation, still had it and dug it out. Mine is a little smaller (size 83). I only recently started using it and love it. It is probably the best seam ripper you will ever use.
Slide the point under a stitch in the row you want to rip.
Lift the tool to break the stitch.
Repeat in a few places.
Place the point under a stitch in the run and pull out the thread.
Viola! You have one long thread on the back that just comes away! (Don't you love pulling out that thread in one motion?)
Sometimes the simplest tools are the best.
You can buy one here.