SIMPLEX. MODEL: 4098-9772 (P/N: 07431568). TRUE ALARM SENSOR BASE W/520 HZ SOUNDER., LOW FREQUENCY ALARM DETECTOR BASE WITH INTEGRAL AUDIBLE SIGNAL FOR OPEN AREA PROTECTION WHEN USED WITH A SIMPLEX UL LISTED HEAD., ALSO SUITABLE AS AN AUDIBLE SIGNAL APPLIANCE FOR FIRE ALARM SERVICE., ISSUE NO. A-72461., DATE CODE: 21 293 V., 86 dBA MIN PER UL268., 24 VDC., 80 dBA PER UL464., MAXIMUM 100° F AMBIENT., FIRE ALARM SUBASSEMBLY S1199., 9006-073 REV L., ORIGINAL SIMPLEX OEM REPLACEMENT PART., GUARANTEED TO WORK PERFECTLY., BRAND NEW FACTORY SEALED PACKAGE., NEVER USED OR OPENED., INCLUDES ONE SOUNDER BASE & INSTRUCTIONS INSIDE A FACTORY SEALED PACKAGE., I CAN SUPPLY MORE PICTURES IF REQUESTED.