System Sensor HW-LF

Low Frequency Sounder, White

Condition: New
Brand: System Sensor
Status: Obsolete
SKU: 72675
Manufacturer Part #: HW-LF
Replacement: HWL-LF


The SpectrAlert Advance series offers the most versatile and easy-to-use line of low frequency sounder and low frequency sounder strobes in the industry. With white and red plastic housings, dual listed for wall and ceiling mounting, SpectrAlert Advance can meet virtually any application requirement. The wall-mount low frequency sounder, and low frequency sounder strobes were designed to address the NFPA 72 sleeping space requirements that require a low frequency notification appliance that operates within frequency range of 520 Hz ± 10% and is of a square wave tone. Like the entire SpectrAlert Advance product line they include a variety of features that increase their application versatility while simplifying installation. All devices feature plug-in designs with minimal intrusion into the back box, making installations fast and foolproof while virtually eliminating costly and time-consuming ground faults.

Additional information

Weight 0.4 lbs
Dimensions 4.70 × 6.40 × 2.50 in



Production Status



  • 520 Hz ± 10% square wave tone
  • Plug-in design with minimal intrusion into the back box
  • Tamper-resistant construction
  • Field-selectable candela settings on wall units: 135, 150, 177, and 185
  • Rotary switch for low frequency sounder tone
  • Universal mounting plate for wall units
  • Mounting plate shorting spring checks wiring continuity before device installation
  • Electrically compatible with legacy SpectrAlert devices
  • Compatible with MDL3 sync module
  • Listed for ceiling or wall mounting


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Selectable-Output Low Frequency Sounder and Low Frequency Sounder Strobes for Wall Applications


System Sensor - Data Sheet