It would go directly on the cold water shut off valve. It'll then have an identical connection at the top to reattach the faucet cold water line (looks like a 1/2" compression). Lastly, it'll have a connection on the side where you can attach the washlet hose. Until you select the washlet, you won't know what size/type that connection is. So you should get the washlet first, and then get a splitter that is 1/2" compression inlet, 1/2" compression outlet 1, and then whatever the washlet needs for outlet 2.