Grip Rite Prime Guard XR4625GR 2-n-1 Concrete Curing Vapor Barrier and Septic Insulator Blanket, 4 Layer Foam 6 25-feet Long High density woven PE envelope coated on both sides for extreme vapor retarding properties. Grip-Rite blankets have a low perm rating of 0.87 Woven PE webbing is sewn all around securing insulation layers to envelope preventing insulation movement Insulation is full edge to edge design with zero insulation voids at the hems PE webbing is perforated with eyelets spaced at 10.0 cm intervals allowing the blankets to be fastened together, or to scaffolding or forms Extreme blankets can be used as an insulated tarp when installed on scaffolding (Note  Grip-Rite extreme blankets are not flame retardant. Check local fire codes before installing)