The UREI 565 Filter Set is a unique equalizer that has four bands and a variety of parameters not seen on most EQs. It is an analog unit and I'm not sure what type of connections it has as the one that I have used was already racked up in a studio. I do know that it has 1/4 inch connections in the front if you want to plug your instrument directly into this. It is indeed rack mountable and will take up three rack spaces in a traditional rack.
Using the UREI 565 Filter Set isn't all that hard, but it did take me a little while to get used to everything going on because I've never really seen an equalizer like this one. The bands are easy enough to use as you simply set the frequency, and then there are a variety of knobs including parameters for range, fine frequency, and balance, appearing more than once for the different sections of the frequency spectrum. If you are a beginner with EQ, this probably isn't for you, but if you know about equalization I think that you'll be able to figure this out without a manual.
The sound of the UREI 565 Filter Set is overall quite impressive. I knew from the start that I would be using a quality EQ as I've never used a piece of gear made by UREI/Universal Audio that I didn't like. This is a suitable EQ for just about any application, but I've only used it on guitars for the most part and it definitely does the job for this. Beyond using this as a traditional EQ, it is great for getting creative with. In fact, I would recommend this more as a creative EQ than a traditional one...
I first used the UREI 565 Filter Set about a year ago or so and have found it to be a very cool sounding EQ. While it can be used for traditional EQ means, I love getting creative with this as it opens up new doors in terms of filtering. This isn't an easy unit to come by and unless you find one in a recording studio like I did, you're going to have a hard time finding one of these. However, if you do stumble upon one of these definitely look into it as I don't think it will cost too much for what you're getting. All in all, the 565 is definitely one of my favorite creative filters out there.