You have one body, we need to take care of ourselves.
I have been hurt on set doing stunts and it is the worst.
Sometimes the costume we wear don't allow you to wear a full kit and you may only be able to pad certain key areas that are taking the hit.
These individual pads are great for that and they are the same ones used for motorcycle safety gear so they can take a hit and not your bones. This allows you to boost up any armour if you are doing harder hits like car hits or awkward falls.