CAS-304/308/312 is a professional linear column speaker developed by SHOW. The front of the speaker has a 1.0mm mesh and a 1.0mm thick aluminum mesh. It can effectively prevent dust from entering the speaker, and the aluminum mesh can well protect the speaker unit from being directly damaged by external forces. The back of the aluminum mesh is covered with white mesh to effectively prevent dust from entering. The box body, upper and lower covers and aluminum mesh are all made of aluminum, which effectively prevents aging and rusting due to long-term use. The surface of the box is sprayed with RAL9016 white UV-resistant powder paint. 3” full-range speaker unit has a straight paper body and PU edge cone. The speaker vibration system is lightweight and highly sensitive. The sound system uses a power transformer to switch the system power, which can effectively protect the speaker. It prevents high-power input signals from damaging the speaker, and multiple speakers can be used in parallel without causing low impedance and damaging the PA amplifier. There are two bracket options for more flexible installation.