Even with with pressure set to 30+psi (which would be necessary for an Atomic-style diffuser), the -H model will *probably* work, but it's only rated to 25psi. The standard and -L models are rated to 105 and 50psi, respectively. For some reason the info at Clippard.com doesn't show this, but if you click the link to the catalog page, you'll see it at the bottom of the page.
Be aware that those are mounted versions, so in case you're checking Evilbay and not the Clippard site, you'll still have to order a mount from Clippard, in which case you're better off buying straight from them. There's no price difference between the standard, -L, and -H, so just get the standard. An example of an inline (not mounted version) would be ET-2-24 rather than ET-2M-24. The main advantage to a mount, for our purposes, is that the inlet is 1/8" NPT, so it's a bit sturdier than a non-mounted version, which has a 10-32 inlet.