Extra long self drilling screws for use in heavy section steel. External coating, fine thread and long drill point.

They are commonly used for timber to steel rails and purlins.

• The Salt Spray Test (DIN 50021 SS)
  Used to test how long a screw can resist an aggressive salt spray environment before corroding.
• The Kesternich Test (DIN 50018)
  Used to test how long a screw can resist an aggressive acid based industrial environment.