Extra loud horn for ALL cars Adapts to single or double-terminal applications Choice of high- or low-frequency horn Replaces original-equipment horn, or can be added to existing horn system. 4" wide, 4-1ǘ" long, 3" high. Install individually or mount in pair to produce a harmonious high/low blast. Horn relay is required when installing 2 horns together. Metal motor housing and ABS thermoplastic trumpet. Includes 360° installation bracket, hardware, instructions. Installs easily for any 12-volt systems.