Flow resistivity for "acoustic foams" might be around 10k ... 20k Pa.s/m3
You can hunt this kind of info, but if the vendor isn't supplying it for their product, you have to wonder how serious they are about acoustics.
(this is in the same area as the middling density rockwool products)
If you plug this number (and the thickness) into a calculator
like this one
You'll get an idea of what you might expect.
Note that simply adding more thickness doesn't help unless the flow resistivity is fairly low.
i.e once you've got (say) 100mm of a typical foam (or a dense-ish rockwool), you don't get a lot more absorption at LF by adding more depth. Although you can by adding an air gap behind the absorber. Or alternating absorber/airgap layers.
100mm of 301 fibre glass (14k Pa.s/m3) will be rolling off by 300Hz & won't be doing much at 100Hz
Porous absorbers that go low - with significant absorbtion at 100Hz - will usually be deep (>500mm) and filled with stuff with lower resistivity (<4000 Pa.s/m3)
There's a
nice table here
Of course, all these broadband porous absorbers will absorb high and mid frequencies really well. So that's something to think about.