The RM-210 Key Extension Unit is a professional-grade accessory designed to increase the operational capacity of TOA’s RM-200X and RM-200SA Remote Microphones. Engineered for use within voice alarm and public address systems, the RM-210 adds ten additional function keys to the base microphone unit, enabling more comprehensive control over system zones, paging areas, or programmable actions. Up to nine RM-210 units can be connected to a single compatible microphone, providing a maximum of ninety extra keys to support complex operational requirements. This makes the RM-210 particularly well-suited for large-scale commercial or institutional environments such as transport hubs, educational campuses, industrial sites, and multi-zone facilities where precise communication management is essential. Each extension unit is designed to integrate seamlessly into existing systems, ensuring consistency and reliability in operation. The RM-210 maintains TOA’s standards for robust construction and long-term performance, offering system integrators and facility managers a dependable means of expanding microphone functionality without compromising efficiency or usability. With its modular approach, the RM-210 supports adaptable communication infrastructure while meeting the demands of high-traffic or multi-zone public address installations.