Whomever built that it's not rising rate, for it to be rising rate (from what I've seen) there would need to be either a larger diaphram for the air (manifold) pressure to act on up top (the end with the adjusting screw and jam nut), or some mechanical tomfoolery internally to do the same, which tends to make the unit taller (shaped kinda like an exhaust pipe coupler).
In that picture it's blown up enough (pixelized) to the point it's not practical to tell which brand it is, as the color will change some when blown up to that extent.
AFAIK they both make one that looks like that (not necessarily identical, but similar enough for me not to be able to tell from that pic
).
