Strap fastener

A buckle for a strap which comprises a rectangular body formed with a window defined by a planar rectangular frame with a fixed bar at an edge of said body, and a pair of guide walls extending generally perpendicularly to said fixed bar, and at least one movable bar in said window parallel to said fixed bar and defining therewith a gap into which a strap can be passed and which can clamp said strap against said fixed bar, said movable bar being provided at its ends with wedge-shaped formations tapering toward the fixed bar, said walls being formed with lateral slots respectively receiving said wedge-shaped formations with clearance and tapered correspondingly toward the fixed bar with substantially the same angle of taper as that of said formations and such that movement of said formations in the respective slots in a direction opposite the direction of taper thereof increases play between the formations and the slots whereas movement of said formations in the respective slots in an opposite direction wedges said formations without play in said slots, said movable bar being wider between said walls than said formations in said directions, said movable bar being provided with longitudinal flutes along an external surface thereof between said walls and which run transversely to said directions, said wedge-shaped formations being provided with flutes along external surfaces thereof which run transversely to said directions.