Button protector for (Biltema) Jumpstarter

I have a jumpstarter for cars, this one [bought in Biltema](http://biltema.dk/da/Bil---MC/El/Batterivarktoj-og-tilbehor/Starthjalp-12-V-900-A-med-kompressor-37905/). Unfortunately it has a on-button that very easily gets turned on if the jumpstarter is just lying in the trunk.

This thing is a button protector, that simply sits over the button to not allow accidental presses.