What are these pieces for? I got these pieces from set 76119 "Batmobile Pursuit of Joker", but the instructions don't specify what the pieces are for. What is their purpose?
According to the official description, these are for customizing the completed build:


  This LEGO Batman toy playset includes 2 minifigures and children can customize their builds, minifigures and weapons with the included pack of 10 assorted Bat elements.