Carbon steel fastener for waterproof membrane and insulation securement on steel substrates. Case hardened carbon steel Durocoat® Resistance 15 cycles Kesternich test according to • EAD 030351-00-0402, A2.4 • FM Approval Standard 4470 Item 1: 1.25 million screw 22 - 24 cm as per available length Item 2: 100K Screw 16 cm Length Item 3: 50K 13 cm Length Please send quotation for both alternatives of screw design, ASAP.