The l39bc 51/11 is a compact 6 W speaker with a perforated gold mask. It has excellent audio performance, built-in mounting clip, easy to install in line. The front part of the speaker is IPx4 waterproof, so it can be installed in a moist environment. The basic function LBC 3951/11 is equipped with a perforated metal mask with a plastic surround, and the color is aesthetic fashion, RAL. The exquisite shape of loudspeaker can be perfectly integrated with modern interior decoration and lighting equipment, and coexist harmoniously. The speaker has an ultra-wide open Angle, which means that only a small number of speakers can cover the specified area. Wide frequency range can achieve better voice and music playback. In addition, the speaker is equipped with a 100v matching transformer, and the jumper connector on its primary winding allows the user to choose the full power, half power and one-eighth power. The front of the speaker (with a special paper speaker) is IPx4 waterproof and can be installed in a moist environment, such as a bathroom, sauna, atrium and swimming pool. Certificate and approval all plastic parts are made of high strength ABS flame retardant material (in accordance with UL 94V0 standard). All Bosch speakers comply with IEC 268-5 power treatment capability (PHC) standard and can run continuously for 100 hours at rated power. Bosch has also conducted simulated acoustic feedback exposure tests to ensure they can withstand twice the rated power in a short period of time. This ensures high reliability of the speaker under extreme conditions, improves customer satisfaction, extends service life, and significantly reduces the probability of failure or performance degradation. Safety in accordance with EN 60065 standard waterproof in accordance with EN 60529, IPx4 standard area certification European CE installation/configuration speaker built-in installation clip, users can easily fix it in the ceiling hole. The ceiling can be between 9 and 25 mm thick. In addition, a template is provided for accurately marking holes in the ceiling. The user can wire the cable through a junction box with a push - in terminal to install it without using any special tools. The junction box can also be used for loop wiring. The transformer wiring attached provides a 6 W rated output power, and can also be easily changed with color wires and junction boxes to provide different power.