USP NVB (Nailable Venting Base) is manufactured with a heavyweight, select fiberglass mat designed and constructed to be strong and wrinkle resistant. The glass mat is saturated with a high quality, non-filled asphaltic bitumen and coated on the underside with a course mineral surfacing to allow for underside venting. USP NVB is designed for use as a mechanically attached base sheet for hot mopped, cold applied and torch applied roofing applications where additional venting is desired in specifications requiring a fiberglass venting base sheet.