JBL Professional Control Contractor Ceiling Speakers deliver high power handling, overload protection and exceptional sound level capability and are packaged as complete assemblies, including integral backcan, front grille and tile bridge support hardware. Innovative design features such as titanium-coated tweeters and JBL’s unique diffraction-horn loading provide broad, even coverage throughout the listening area. Installation of JBL Control Contractor Ceiling Speakers is quick and easy and can be accomplished without requiring access above the ceiling. Bracketry for suspended ceilings is included. The speaker is held securely in place via mounting ears which rotate into position and lock into place. Inputs are attached to a removable locking connector (included) which can be prewired before installing for ultra-fast snap-on installation. This model contain formed steel backcans and are suitable for use in air handling spaces per UL1480 and UL2043.The Control 19CST has a special subwoofer-band transformer for use on 70V or 100V line distribution systems. The Control 19CST uses advanced proprietary technologies to produce powerful bass from a low profile in-ceiling design.