Versico’s Purlin Fastener is specifically designed to secure membrane and Pressure-Sensitive (PS) RUSS to structural steel purlins in Versico’s metal retrofit roofing systems. Purlin Fasteners are compatible with 2" (50.8mm) Polymer Seam Plates and 23/8" (60.3 mm) HPVX Plates. Minimum penetration is 1¼" (31.75 mm)