Abstract: An article of insulation, especially adapted for insulating corners, is provided. The article is constructed in the form of an elongated flexible sheet capable of sustaining and retaining at least one longitudinal fold therein and having generally a beginning end and a closing end and first and second, generally opposite longitudinal sides thereof. Each longitudinal side has a plurality of protrusions or tabs extending outwardly therefrom along the length of each side, with each protrusion being separated from adjacent protrusions such that, upon folding the sheet longitudinally along its centerline to form overlapping halves folded upon one another, the protrusions along the length of the first side overlap the separations along the length of the second side, and vice versa. The article has a second fold extending longitudinally thereof along the bases of the protrusions such that the overlapping protrusions form substantially a right angle with the remaining portion of the sheet.