Speakers come in a range of sizes, materials and styles. Construction is generally made from various metals through to more lightweight nylon composite materials. The larger metal designs have the advantage of powerful output while the lighter nylon versions have a weight and size advantage – this is especially helpful for vehicles with little mounting room and also for mounting in covert unmarked vehicles so as not to be seen. Speakers are all generally 100 Watts RMS, making them loud but also suited to any siren in the Britax range. If fitted with an additional amplifier, speakers can be installed in pairs to increase the volume and impact of the emergency vehicle in traffic or high speed operations.