Hovering off the ground can require a lot of power depending on various parameters (hover surface conductivity, payload, Hover Engine efficiency just to name a few). The battery can get warm (120°F or 50°C) under normal operation. The purpose of the timer and fuse should prevent the battery from getting dangerously hot.

The green square is called magnetic viewing film, which is a powerful tool that can help visualize magnetic field. It helped us better understand magnetism and discover Magnetic Field Architecture (MFA™). For more information, see the appendix on Understanding MFA in the User Guide.