The purpose of the Shield is to protect part components, or the user, from debris, friction, and overheating when operating. A shield can accompany all components of your model, including a tube shield, muffler shield, or pulley shield, as examples. It is similar to, sometimes synonymous with, guards or covers. Some shields can wear down over time from collisions, or debris, and it is important to replace if needed for user safety and the protection of parts.