These are partially threaded hex cap screws with all dimensions conforming to DIN 931

The hot-dip galvanizing provides a strong protective coating

9/16 x 6 1/4 ITM SDS Plus Hammer Drill Bit

Over-sized threads are wider than gutter spikes

5/16 x 8 Strong-Point Wafer Head Knurl Type 17 WAR Coated Timber Screw - Carton (250) Titen HD® Countersunk Head Style Heavy-Duty Screw Anchor 316 Stainless Steel These are partially threaded hex5 16 x 8 Strong Point Wafer Head Knurl Type 17 WAR Coated Timber Screw Carton (250) High performance timber screws featuring a wafer head design. Dimensional specifications: 5 16 x 8 with 5 16 diameter. Features knurled thread pattern for superior grip and reduced installation torque. Engineered with Type 17 self drilling point that eliminates pre drilling requirements in most applications. Exterior wood structural screws for outdoor applications.