This is a reinforcement brace for the Tamiya Boomerang. You use it at the front where the upper arms are mounted. This is particularly useful for protection when either side of the front takes a hit.
Technically you can use it on a Big Wing as well. However, longer king pins will be necessary for the arms.
upgradeparts-tamiya-boomerang-front-upperarm-reinforce
On a Boomerang:
On a Big Wing:
