It depends what kind of snap you apply.
http://www.sailrite.com/easearch#!&ea_q=snap%20tools
I now own this tool !!! OMG I wish I had found it 40 years ago. a perfect set every time.
I ordered the tool and the bench mount for easy pressure to apply the snaps. I use a fast clamp to secure it to a table top.
I can’t tell you hoe many snaps I have taken off with a screwdriver/wire cutter/drill! Now, never again.
This site has wonderful how to videos on many things.
Plus: this is their new invention
http://www.sailrite.com/easearch#!&ea_q=snaprite%20tool