While shopping for a horn, make sure its decibel is perfect, as per the water vehicle you plan to install it on. For the electric kind, it should be easy to fix. Also, consider the after-sales service during the buying process itself. Storing and transporting it should be simple. The horn should be lightweight and not too bulky since you will be installing it at a height. The size should work well as per the space you intend to use it in.