System Sensor 5601P 135F Fixed Temperature and Rate-of-Rise 2-Wire Single-Circuit Mechanical Heat Detector is a mechanical heat detection device designed for reliable fire alarm activation using both fixed temperature and rate-of-rise sensing. It supports flexible installation options and is built for compatibility with a wide range of back box configurations in residential and light commercial applications.

• Fixed 135°F activation with combination rate-of-rise (ROR) sensing for dual-trigger fire detection
• Single-circuit, 2-wire design for straightforward installation in conventional fire alarm systems
• Reversible mounting bracket supports flush or surface mount installations across multiple back box types
• Compatible with single-gang, octagonal, and 4-square back boxes (with adapter ring)
• Post-activation indicator drop feature clearly identifies the alarmed unit for quick system inspection