Product Description GRK's TRIM RT head composite screws are an excellent choice to prevent the dimple or mushrooming affect that sometimes appears. The reverse thread design is available with lengths from 2-inch to 3-1/8-inch. Most material splitting is prevented by the Trim head screw's small head and W-cut thread design. Pre-drilling is usually only necessary in extreme hardwoods like Mahogany or Ipe'. Some sizes are availabele in PHEINOX stainless steel. From the Manufacturer GRK's TRIM RT head composite screws are an excellent choice to prevent the dimple or mushrooming affect that sometimes appears. The reverse thread design is available with lengths from 2-inch to 3-1/8-inch. Most material splitting is prevented by the Trim head screw's small head and W-cut thread design. Pre-drilling is usually only necessary in extreme hardwoods like Mahogany or Ipe'. Some sizes are availabele in PHEINOX stainless steel.