Have you got a jar key?

Sometime ago I was given this little gadget - I wasn't even sure what it was for. Then I discovered it was really handy - it helps you undo jars with no muscle power needed.

All you do is put it on the edge and gently push it, you will probably hear a little pop.  That will often be enough to be able to open the jar - but if it isn't just move the hoodacky (actually called a jar key I found out) around just a little and do it again.  Don't press too hard or you might bend the lid out of shape.