- Translated as “Sound” in Japanese, the OTO Style Horn is built to the same high-quality standards as other PIAA horns, but at a more affordable price point. This value-oriented horn complies with various international standards making it durable and reliable against extreme temperatures, corrosion, and water submersion. Built for developing countries, it lasts even after 1 million cycles (4-second horn on/off bursts)—twice the industry standard.The OTO Style horn is sold as a set of two and features a deep bass note (listen to how it sounds and compares against the PIAA Superior Bass and Slender Horn in the video below) and has a sound frequency of 400 Hz + 500 Hz with a maximum output of 112 decibels.