The Inward Connections Tube Step Equalizer is a Vac Rac series module. I've used it inside of the Inward Vac Rac 4000, and I'm not sure about it's compatibility with other casings. It does have it's own connections on the module, including inputs and outputs in both 1/4" and XLR forms. It isn't rack mountable (or usable) outside of a Vac Rac system.
The Inward Connections Tube Step Equalizer is made up of three bands. Each of these bands has a series of fixed frequencies to choose from as well as a gain knob, making it semi-parametric. Each also has a button for shelving the bandwidth, and there are high and low pass buttons as well - the high pass at 50 Hz and the low pass at 15 kHz. I've never seen the manual for this module, but one shouldn't be necessary if you have any experience at all with equalization.
The sound of the Inward Connections Tube Step Equalizer is brilliant! It's not a super clean sounding EQ as it is indeed vacuum tube based, giving it a rather thick sound. For this reason, it's best suited for beefing up a sound or bringing out a certain quality in a sound rather than using it for super specific frequency cutting or boosting. In general that's going to be the idea with semi-parametric EQ's, but especially so here since you're working with tubes. I've only had the chance to use this EQ for vocals while tracking with a chain of all Inward Connections modules from the Vac Rac, and I really can't say enough about how awesome it sounds!
Unfortunately not too many people will get to experience the Inward Connections Tube Step Equalizer, as you need to have a Vac Rack casing in order to use it. This is quite a little investment, so only professionals should be able to realistically consider this. Inward makes four modules for the Vac Rac 4000, with this being one of them. If you throw this EQ in with their limiter and tube preamp, you pretty much have the perfect tube chain for recording any and everything!