A Marine Grade M8 x 70mm  Machine Screw - perfect for use on a Europe Gooseneck. 

You may also want to take some gooseneck and boom bushes to complete the perfect fit as the Ceiligh gooseneck and boom actually both have a 12mm hole - hence don't forget the bushes.   

NOTE: Any Rooster web wide discount offers or promotions do NOT apply to all Europe spars, sails and fittings.