Don't use this regulator! It's not a true pressure regulator, it's simply a valve (notice it's called a flow regulator). If there isn't constant flow (like in a paint spray gun) the pressure on both sides will quickly be the same.
If you want a cheap secondary regulator this one from harbor freight will work
. I've gotten them when they were on sale for $4.99.
For these air tool regulators, you'll need to replace the gauge with a 0-30 psi one because the ones that come with them don't have the resolution at the pressures that we use for beer.