Product Description: Hammer-driven helical fixing for securing counterbattens to rafters in warm roof applications without compressing insulation. Engineered with a constant helical pitch to prevent splitting/bouncing of timbers and to interlock perfectly for maximum performance. Nominal 9mm2 CSA. Meets the technical requirements of the NHBC. Fixings are to be be installed vertically along the centre line of the counterbatten to rafter arrangement. Use of the Thor Helical Alignment Tool is recommended where insulation depths exceed 70mm.