What is one indicator that a device may be a bomb, based on the PIES approach?

The presence of timers is a critical indicator that a device may be a bomb, especially when applying the PIES approach, which stands for Pressure, Indicator, Environment, and Size/Shape. Timers can suggest that an explosive device is designed to detonate after a predetermined period, indicating intentionality and the potential for harm. When assessing a suspicious device, the existence of a timer raises immediate concerns regarding safety and necessitates a cautious approach. This feature is a key factor for responders to evaluate because it clearly signifies an operational component of a potentially explosive device.

While the other options like color, shape, and physical weight might give some information about a device, they are not as definitive as the presence of timers when it comes to identifying a bomb. Timers inherently imply a level of sophistication in design that suggests the device is not merely benign.