The Bosch high efficiency horn speaker provides superior voice playback and sound transmission efficiency and is suitable for outdoor applications. They are ideal for sports fields, parks, fairs, factories and swimming pools. LBC 3481/12 is a circular horn speaker, while LBC 3491/12 is a rectangular horn speaker. Both loudspeakers have a power of 10 W and are made of ABS material. LBC 3492/12 is a 20 W round horn speaker with a large horn with a diameter of 354 mm. It is made of aluminum material and ABS material, which is not only strong but also portable. The horn edge is covered with PVC profiles to prevent damage from impact. LBC 3493/12 is a 30 W round horn speaker with a large horn with a diameter of 400 mm. It is made of aluminum material and ABS material, which is not only strong but also portable. The horn edge is covered with PVC profiles to prevent damage from impact. Basic function all four models can be directly connected to the output of 100v circuit, and the coating is light gray (RAL 7035). These horn speakers are waterproof and dustproof. The horn speaker is attached with a 100v transformer, and the jumper connector on the primary winding can be used for different power Settings. By connecting the amplifier output to the corresponding connector, the user can easily select the rated full power, half power, or quarter power (range of 3 dB). The horn loudspeaker is equipped with two meters of four-core cable. Each cable core USES a different color and is connected to one of the sub joints on the transformer. The horn loudspeaker is equipped with a strong adjustable steel mounting bracket to guide the sound beam accurately. All Bosch speakers are certified to meet IEC 268-5 power handling capacity (PHC) standards and can operate 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. Safe compliance with EN 60065 standard flame retardant compliance UL 94 V0 standard waterproof and dustproof compliance EN 60529 - IP65 standard area certification European CE compliance statement CE