Little Labs' VOG (Voice of God) Analog Bass Resonance Tool is a 500 series module that is a unique bass processor. It's designed for use with bass instruments, but it's definitely suitable for use for other applications as well. Since it's a 500 series module, it doesn't have any of it's own connections or power supply and is only rackable in a 500 series rack casing.
The make up of the Little Labs VOG isn't complex at all, but it did take me a couple of minutes to get used to how the parameters will actually affect your sound. These parameters include knobs for amplitude and frequency, and switches for adjusting the frequencies. I haven't seen any manual for the VOG, so I can't speak about it, but it might be a good idea to have some specs around when getting acquainted with this.
I couldn't possibly say enough about how cool sounding the Little Labs VOG is. It adds a huge amount of low end clarity and fullness to bass guitar and other low end applications. It's hard to describe the sound without actually hearing it, but basically it enhances the low end a great deal to where it sounds rounder and fuller. This is almost one of those 'instant' type of enhancers, only with more to work with. The only thing I can think of to could compare it to would be something like Waves' R-Bass, which is also a bass enhancer, and the VOG sounds a lot clearer and fuller.
The Little Labs VOG is really an amazing piece of gear. It's the first 500 series module to be made by Little Labs as well. It's easy to use and offers up a whole helping of tone. If I had access to it all the time I'd be using it on all of my mixes, but alas I don't yet own one of these. The price is actually really inexpensive for a processor of this caliber. Even though the VOG maybe isn't a necessity, it's an awesome luxury to have in any studio.