TOA's CS-64, CS-154, and CS-304 speakers are for outdoor-use, they use wide-range horns that can provide background music or paging announcements which have high quality sound. They are designed to produce high output with an increase of the speaker acoustic conversion efficiency, by the use of a horn in combination with a cone speaker. The CS-64 employs an exponential horn, while the CS-154 and CS-304 use constant directivity horns (90 horizontal) to control sound directivity, realizing uniform and clear sound dispersion over a wide area. These wide-range speakers are also designed to stand up to the rigorous weather conditions when installed outdoors. The speakers' ABS resin enclosure is light in weight, structurally strong and resistant to impacts. Since the enclosures are also treated with weatherproof polyurethane resin paint, they are extremely resistant to the effects of ultraviolet light, ensuring many years of reliable operation. The speakers also comply with IP-64 Standard requirements for dust proof and waterproof capabilities. In addition, the internal speaker parts feature a special weatherproof treatment to enhance the waterproof properties of the entire speaker. Stainless-steel brackets and screws further protect the unit from rust and corrosion. Speaker impedance can be easily changed externally with a rotary switch, facilitating changes in impedance during and after speaker installation.