Approvals include: UL Standard 464, Factory Mutual (FM), California State Fire Marshal (CSFM), New York (MEA) and Chicago (BFP)
Low frequency aluminum shells for better audibility through walls, doors and other structures
Integral RFI suppression to minimize included noise on the NAC circuit
Built-in trimplate makes semi-flush mounting simpler and less expensive
Screw terminals permit fast in-out field wiring of #12 to 18 AWG wire