The Crest Fixing Screw with Double Thread design is engineered for roofing applications where enhanced holding power and sealing performance are required.The upper thread features a larger diameter, delivering superior pull-out resistance when fastening thin metal sheets. The scratshank (knurled shank) helps remove excess swarf during installation, preventing damage to the washer and ensuring long-term water tightness.Available with various threadless shank lengths, this screw is ideal for accommodating insulation layers in insulated panel systems. Manufactured in Taiwan under strict quality control, it ensures consistent performance in demanding construction environments.