Deerwood Round Washer Head Assembly Screw for wood. The round washer head design is one of the most versatile screw head designs. It combines the advantages of the round or pan head with the addition of an integrated washer to increase head diameter and prevent overdriving in softwoods while providing a maximum bearing surface. The patented Lo-Root coarse thread design offers many advantages- quick starting, reduced splitting, less drive torque and a tighter hold. The threads are dry lubricated for ease of installation with reduced torque and effort. These fasteners feature the patented Recex Square-Phillips combo recess drive designed to offer the dependability of a square drive (aka Roberston Drive ) recess with the convenience and after-market serviceability of a Phillips drive.