Designed for emergency communications systems, the System Sensor SpectrAlert Advance Clear Dual Strobe and Clear Dual Strobe with Speaker Expander Plates combine the functions of two to three notification devices on a single mounting plate and back box, lowering the overall cost of the installation while requiring fewer devices on the wall. Easy for a single person to install, the plates include a UL 1971-listed (Signaling Devices for Hearing Impaired) clear lens strobe for public mode signaling. Clear lens strobes are also compatible with colored lenses for UL 1638 Private Mode General Utility Signaling. They can be used in 12V or 24V systems and can be paired with a SpectrAlert Advance strobe or speaker strobe.