Internal Nipple Spoke Wrench Park Tool SW-16 3.2mm SquareInternal Nipple Spoke Wrench Park Tool SW 16 3. 2mm Square Some wheels feature spoke nipples accessible only through holes on the outside of the rim. The SW 16 is specifically designed to access these hard to reach internal nipples. Features a comfortable dual density handle and an extra long shaft for deep aero rim cavities. Features Sized for 3. 2 mm square shaped internal nipples Shaft length: 825 mm (3. 25") Shaft outside diameter: 6 mm (0. 24")