Park Tool SW-15 3 Way Internal Nipple Wrench
Park Tool's innovative 3-way "Y" wrench featuring three different sized wrenches to fit internal spoke nipples. Featuring a 3.2mm square drive, plus 5mm and 5.5mm hex sockets that slip perfectly into the tight surroundings of most rims. The SW-15 works with wheels made by numerous manufacturers including, but not limited to: FSA, Blackwell, Planet-X, HED, Rolf, Bontrager, Campagnolo and Mavic.
Note: Wheel manufacturer's specifications change without notice.
If you have some deep v carbon aero rims without any nipples sticking out, then there's a good chance you'll need this tool to do any repairs. There aren't any great substitutes for this thing. It works well.