For carrying and storing 9 by 12 paintings. Very lightweight. Constructed of sturdy 3mm corrugated cardboard with an -inchangular channel-inch design in polystyrene to protect the edges of your artwork. Each box holds two stretched canvases or four panels. Perfect for keeping your plein air paintings dust-free while drying or in storage. Sold in packs of three, these convenient wet painting carriers are shipped flat with instructions for easy assembly.