This little widget is called a "variable power divider" and is made by Mini-Cuircuits, model ZSC-2-2-75-2.  It is for 75 ohm systems, and allows you to adjust the power split between ports. HOWEVER, what is more useful, is that the top and bottom come off this thing, and you can scrub out the guts and build your own circuit inside!  Very pretty little box, already drilled for BNC's etc. These are new old stock, from an unfinished project. Several are shown, you are buying 1 at a time.   

 Please see my other items for more RF goodies and weird stuff. Remember, I gladly combine items to save you shipping costs, so ask before you pay. I ship worldwide!