These are compliant with the Australian Standards 1926.1  for swimming pool barriers.  The cap is compliant because they create a surface that is more than '60 degrees' and makes the hinge non-climbable.   The cap also reduces the flat surface of the hinge that could be used by a toddler for climbing. 

These caps are simply screwed in to the top of the hinge.  

Note: On some hinges a small cap covers the top as shown in the photo. This can be removed and the compliant cap added in its place. 

(The screw on the top of your existing hinge can be used to attach this cap). 

Postage is by Courier (tracking included).   Express postage can be arranged for an additional cost. 

Local pickup - Mentone