Engineered for applications with limited plenum space incorporating a SoundTube-specific shallow backcan with an installed depth of 3.5inches. One 8inch (203mm) polypropylene woofer with butyl rubber surround and one 1.0inch (25.4mm) silk dome tweeter. Easy-access six-position tap switch for 25/70.7/100volt and 16ohm transformer bypass settings allows for easy ordering, stocking and installation. Reduced amplification costs and maximum efficiency of 88.0dB sensitivity, 16ohm impedance and a sealed enclosure. Superior voice intelligibility with an average coverage angle of 105° (2–10kHz, independently verified). Cost-effective 16ohm settings allows for the use of multiples of two, four, or six speakers in a system using a standard amplifier without a transformer. Incorporates a painted steel grille with rust inhibitor for lasting durability. Ceramic input terminal accepts up to 10gauge plenum rated signal wire and includes thermal fuse. Suitable for use in voice alarm applications subject to EU regulations EN60849 and BS5839-8. Adaptable to ceiling thicknesses ranging from 0.04 inch (0.9mm) to 1.60inch (40.6mm). UL 1480 (UEAY) and 2043, cUL, CE (EMC Directive 89/366/EEC, EN55020, EN55013) approved. Included accessories: tile bridge, UL-listed 0.5inch conduit clamp, paint shield and two wire nuts.