What kind of plumbing part is this and what is it for?

Hi! I just found something that looks like a plumbing part. Don't know for sure, and I am looking online for Woos and Soom. There is nothing that's helping me lol. Does anyone know what it is for? https://sphotos-b.xx.fbcdn.net/hphotos-ash4/293014_397098403677245_1787608370_n.jpg