Type-17 point for fast starts. Coarse threads approximately 2/3; up the shank draw board tightly to the substrate. Pre-drilling recommended near board ends to prevent splitting. Use with stable woods and wood substitutes when screw heads need to be hidden. #7 screw has 0.230" head diameter and #1 square drive recess. #9 x 3 1/2 " screw has 0.250" head diameter and #1 square drive recess. #9 x4" screw has 0.250" head diameter and #2 square drive recess. Choose type 316 for seaside applications and superior corrosion resistance.Simpson Strong Tie Co., Inc.