AccuVent 22.5'' x 41'' 24'' o.c Flame Retardant PVC Attic Vent 50 Pack ACBP11739 50 Pack Installs quickly and easily with just a few staples. Prevents insulation difting. Made of 100% recycled, flame-retardant PVC. Meets ENERGY STAR Thermal Bypass inspection checklist. Prevents ice-damming and growth of mold and mildew. Accommodates glass, cellulose, and spray foam insulation. Reduces insulation labor. Creates a boundary for insulation allowing for fullest top-plate coverage.