Head: Hex Flange. Finish: Specialist Anti-Corrosion Green Treated. Timber Fixing Screws Single Part Thread Hardened Screw. Specifically Used In Decking Construction. Extremely Coarse Thread Offering Increased Holding Power In All Types Of Decking Timber. Acq Resistant Exterior Grade Coating With Up To 1000 Hours Salt Spray Protection. Also Widely Used In Exterior Timber Fencing And Landscaping Applications.PTDFORDIR20TF250