May be used with TPO and should only be installed on horizontal surfaces using an appropriate Mule-Hide fastener below the roof membrane providing additional securement at angle changes. RUSS is secured with Mule-Hide EHD (#15) or HDP (#14) Fasteners and Mule-Hide 2.4" Seam Plates. This product requires the use of TPO Tape Primer or Low VOC Tape Primer.