Knog Oi Classic is a bicycle bell that defies the design of normal bells and comes with a modern look, perfect functionality and unique tone. The bell is unique in its stylishness, but also in the choice of materials that embody the rider's personality.The model comes with an Allen key for mounting in the package. And it fits two handlebar diameters.The Oi small bell fits 22.2 mm handlebar diameters, which include mountain bikes (near grip), BMX and classic city bikes. The large Oi bell fits handlebars with a diameter of 23.8 to 31.8 mm, such as road bikes and some city bikes.