It's a variation of one I saw on thebrewingnetwork.com forum. Mine is 3/4" copper only because I had some in the garage. Most I've seen are PVC. It is definitely a time saver for sure, and it makes cleaning kegs very easy. I no longer dread the day of keg cleaning. Ultimately, I'll build another one, and then I'll have 2, one for cleaning, the other for sanitizing.
In the future, I am also going to use this submersible for my wort chiller. Rather than run tap water continuously through the shirron, I am going to fill my tub with ice water and use the pump to recirculate the ice water through the chiller. Less water, and faster chilling. Win-win situation, especially since I don't have a sink set up in the garage, during a -20F brew day, I don't have to find creative means of disposing of water.