I've discarded the tag, but this item is in beautiful, like-new condition, having only been tried on. The following is from the mont-bell HP: This is an optional item that can be added to a regular backpack to create a Ventilation Back Panel (V.B.P.) that allows wind to pass through the back, reducing stuffiness. The back panel, which directly touches the back, uses a mesh material with excellent breathability. By creating space with a metal frame between the backpack and the panel, breathability is improved, and a comfortable carrying experience is achieved. It can be easily attached with the top, bottom, left, and right tapes and buckles. [Material] 210 denier Ballistic® nylon, mesh, steel frame [Weight] 298g [Color] Black (BK) [Size] Height 45 x Width 28.5 x Depth 6cm [Back Length] 45cm [Compatible Models] Daypacks with a back length of 45-53cm and a capacity of 20-30L (approximate)