Recently I have found myself grabbing the F1 when heading out.
It is a splendid knife with a huge fan base.
The knife comes with a choice of sheaths.
I have the fully closable leather one and the zytell one.
The zytell version features a little catch which holds the knife in place. Of course there is also a clasp to secure it too.
Recently it has not been as tight as I would like so I have added something.
A strong rubber ring which keeps the catch tight. Now the knife cannot jump out of the sheath if un clasped which is handy if you are using it a lot and don't want to keep pressing the clasp closed everytime.