Keep file folders upright in partially full boxes; available in letter and legal sizeSturdy B-flute corrugated support is adjustable to take up 1/3 or 2/3 of a box. Prevent file folders from slipping down in the box. Designed to sustain the weight of heavy folders. Can be flattened and re-used.Ship-flat design saves you space and shipping cost.Specifications: Acid-free pH 7.0 - 7.5 B-flute corrugated (exceeds 200 lb. test) White Unbuffered6 per package.Note: Not intended for long-term storage.