These springs are for letterboxes which use a spring on both hinges as shown in the additional pictures.  The springs are handed - the spring for the Right Hand hinge is different from the spring on the Left Hand hinge.  The springs are made from 1.4mm diameter wire, giving the letterbox flap a firm feel.  The internal diameter of the coil section is 5.0mm, making the springs suitable for rods up to 4.5mm diameter (the coil diameter decreases slightly as the letterbox flap is opened).  Please see the extra photographs for full dimensions.  Please note there is a slight colour difference between the Left Hand Spring and the Right Hand Spring.

Please note we do not sell these springs on Amazon.