The Urei / JBL 7110 is a limiter/compressor from sometime in the 1980's. It's an analog piece of gear and I'm not sure what types of connections it has since the studio that I used it at already had it hooked up. It will only take up a single space in your rack case.
The make up of the Urei / JBL 7110 is more in depth than your average compressor/limiter, but still there's not too much more than normal to be aware of here. The parameters at play here include knobs for threshold, detector, attack, release, ratio, and output level. I don't think a manual is necessary here, but I'm sure you could find one somewhat easily if you need it.
The sound of the Urei / JBL 7110 is pretty decent, and will do a good job for you if you're using it on some things, but overall it's nothing too special in my opinion. They are the kind of compressors that you might want to have in your studio, just so there are options and if someone wanted to compress a lot of things going into tape, would have extras to work with past your main guns. These do sound good, but I would probably only compress a little with these on things like tom tom drums and other more heavy hitting sounds, as opposed to using them overheads and vocals.
I'm not sure how easily you could get your hands on a Urei / JBL 7110, but unless you've already got some killer compressors and are just looking to add to the collection, I probably wouldn't recommend buying this as your main compressors. Maybe in a small home studio I could see it, but even so I think you could get some plug-ins that would be good enough when compared to the 7110. I don't know what these will run you, but I wouldn't spend too much money on them personally. They'd be good to have in a professional studio as just-in-case compressors, but other wise I don't know if they're worth having this day and age.