This stainless steel boom gooseneck is required equipment on the Skerry, Northeaster Dory, PocketShip, John's Sharpie, and Mbuli Proa booms. The 1/2"-inch diameter tang/rod engages the boom. It's universal joint has enough play that you can sail 10 or 15 degrees "by the lee" without damaging your boom.
Mounting plate measures 1-1/2" x 3".
Fasten to mast with four #8 panhead stainless steel screws.