How do I identify my closet system (or do I even need to)?
search for "locking shelf pin" and you will get what you need. 



They have a clip that holds the shelf board from tipping. 

Most shelf pins are made for a 1/4 inch hole, but  not all. Take one of your pins to the home improvement center and compare it to the 1/4" ones there to make sure of its size.