Hammer driven fixing for securing structural plywood composite insulation board on flat roofs.Suitable for 96mm to 126mm panels.Material: High tensile steel “ zinc plated / teflon coated.FeaturesUnique, one-piece, helical fixing.Rapid, easy, hammer-driven installation.Self-tapping action for excellent holding power.Avoids the risk of splitting timbers.Large 20mm diameter head.Strong 8mm diameter fixing.Normally no pilot hole required.Minimises insulation compression.Resists wind uplift forces.Improved thermal bridging.Approved by major insulation suppliers.