He's talking about a "UVSJ". Which stands for
Uhf
Vhf
Splitter
Joiner. It's a very common device, and has been available for more than 40 years. No secret about it, he probably figured you already knew this.
It kind of looks like a small sized splitter, but it's frequency selective. If you feed a Uhf antenna into the Uhf input, it ONLY allows Uhf signals to pass through. Vice-versa with the Vhf input. Or, if you feed a combined Uhf/Vhf signal into the "line output" it separates them into the particular band. That selective isolation makes it better than a standard splitter, which passes all signals through all inputs or outputs and can cause clashes.
It's a very common device, and has been available for more than 40+ years. No secret about it, he probably figured you already knew this.
http://www.solidsignal.com/pview.asp?p=uvsj