The ported plastic carboys are pretty cool in that you can eliminate having to rack out of them. However, you need this tool to attach the nut onto a plastic ported carboy from the inside.

The wrench has a specially molded hex nut to hold the 5/16 inch barbed (FE347) or 1/2 inch barbed (FE347A) spigot nut, and a long handle so you can reach to the bottom of the carboy. The spigot wrench can be reused, you only need it during the installation and/or removal of the spigots.