Mobile radios and portable radios can both be defined as a radio small enough for a responder to carry at all times.

The statement regarding mobile radios and portable radios suggests that both types of radios are small enough for a responder to carry at all times. However, this is not accurate. Mobile radios are typically installed in vehicles and are larger in size, making them less portable compared to portable radios, which are specifically designed to be carried by an individual. Portable radios are compact and lightweight, allowing responders to have hands-free communication while on foot or in various situations where mobility is essential. Thus, the correct understanding is that while both devices serve critical communication functions, only portable radios meet the criteria of being small enough to carry at all times.