A clasping device comprised of a frame and a manipulatable tongue pivotally connected to the frame for movement between released and fastened positions and having first, second and third cross pins and a barrier plate. A flexible strap is threaded through the tongue in such a manner as to extend, when the tongue is in the released position, through a clearance between the barrier plate and the second cross pin, past around and in contact with the second cross pin thereby forming a loop around the second cross pin, and back past beneath and in contact with the first cross pin, so that when the strap is drawn taut as the tongue is pivoted towards the fastened position portions of the strap one on each side of the strap loop are urged in overlapping relation against the first cross pin to provide substantial frictional resistance to the relative movement of the strap loop after the strap is tightened with the tongue held in the fastened position.