CSD-218 series photoelectric smoke detectors are designed in accordance with UL217 EN14604 and manufactured under the best quality control . The CSD-218 series alarm are adopted the reliability UL-certificated infrared components. Product Features: Photoelectric sensing technology Low-sensitivity warning • Low-battery warning • Battery case at the back of a detector for easy removal of a battery • SMD circuit board design-satisfactory quality and reliability guaranteed • Test button verifies battery and alarm operation • Sounding a loud alarm signal of exceeding 85db in alarm mode