A bottle cage is device used to affix a water bottle to a bicycle. Composed of plastic, aluminum, stainless steel, titanium or carbon fiber, it is attached to the main frame of a bicycle, the handlebars, behind the saddle, or, in uncommon cases, the fork. Most modern bicycles have threaded holes in the frame to hold the bottle cage, often called braze-ons even though they may be welded, glued, riveted, or moulded into the frame material. Clamps are necessary on bicycles not so equipped, such as older or less expensive models.