Abstract: A fastener of the nail type adapted to be made in one piece from a narrow strip of sheet metal and composed of a quadrilateral, preferably, generally square, flat head with a single pair of prongs integrally projecting generally perpendicularly from the underside of the head and struck therefrom so as to form a single pair of elongated spaced generally parallel slots in said head, which slots are staggered longitudinally relative to each other and have relatively adjacent lineally offset inner end portions at the medial portion of said head and relatively remote outer end portions adjacent a pair of diagonally opposed corner portions of said head and which extend at acute angles to adjacent sides of said head.