Abstract: A sliding buckle for straps with a largely U-shaped base part in which a wing is mounted for, together with the U-shaped base part, encircling an aperture intended for a strap extending through the aperture, where the wing is mounted pivotably about an axis so that pivoting of the wing about the axis reduces or enlarges the aperture, where pull from a strap bearing against the rear wing section of the wing and having a direction with a component perpendicularly to the base part forces the wing to pivot about the axis in order thereby to reduce the aperture for securely locking the strap in the aperture.