E-Curbs are designed for use on granulated modified bitumen, asphalt and coal tar B.U.R. (built up roofing). E-Curbs are specified for PVC, EPDM, PIB, and TPO single play roofing membranes. E-Curbs are highly versatile for sealing penetrations around solar panel mounts, HVAC, Electrical, and any type of structural supports. TPO Primer is required for use with TPO single-ply roof membrane