The Silver Streak Express DD is the perfect addition to any truck, RV, etc. This attractive horn is designed with an air chamber that will produce a powerful echo sound that replicates a locomotive. Installation is made easy with Wolo's heavy-duty compressor and flexible inlet air fitting. The trumpets are all metal triple chrome plated to withstand all weather conditions. The metal base secures to the vehicles using a rubber gasket and stainless steel bolts, providing a water tight installation. Packaged with all needed parts for installation, nothing else to purchase. English / Spanish instructions included.