Headset spanner for a Brompton

Just the other day while my wife was riding her bicycle, we found out that her headset was loose. Luckily we were near a bikeshop owned by my friend and we went there to have it tightened. He had a wrench like this and after that incident, I told myself that I would buy a similar spanner to fix my own headset should it come loose. So after shopping online and spending about $7, I now own a headset spanner. It is is pretty good and fits my Brompton well. I am looking at getting another one so I can use both spanners in unison to tighten my headset.