The SF531A (SF-531A) Wireless Emergency Call station features the great range and reliability of 900MHz signaling. This unit can be wall mounted near any resident location for call placement (stainless steel and other metal fixtures may interfere with the signal transmission). Calls are latched locally to ensure that residents receive direct staff attention. The device includes a call assurance LED. The pull cord supplied may be used for emergency call activation, or if desired, the large 1.1" (28 mm) red pull-down lever may be used. The SF531A (SF-531A) features a fully supervised RF link to ensure reliability and to monitor battery state. The battery is a customer replaceable 3V lithium.