Flat Wood Screw Silicon Bronze Frearson Drive. These Flat Head Silicon Bronze Wood Screws are Excellent for Many Boat Building Applications. Frearson Drive Which is Very Similar to Phillips Drive Full Body, Tapered Shaft for Better Fastening. General Industry Standard is that they are 2/3 Thread on the Shank Silicon Bronze is an Alloy Made up of 95-98% Copper Plus a Small Amount of Silicon. This Material is Highly Resistant to Seawater Corrosion and is used Extensively in Wooden Boat Building and Planking of Boats. Please Contact our Sales Department for Bulk Pricing and Availability.