4mm Corrugated Plastic Sheets, Short Flute, 18" wide x 12" high. Light-weight PolyPro plastic ideal for temporary signage. Available in white. Stakes sold separately.
"Short flute" refers to the orientation of the sign. Fluting always runs vertically with a sign (so the stake struts can be inserted into it). Short flute means that the sheet is wider than it is tall.