Specifications: You will feel convenient to use it, easy to install and disassemble. It is multifunction for many purpose such as mountain bikes, road bikes, bicycles. The extension frame is made of high quality ultra-light aluminum alloy lightweight, durable, not easy to rust or fade and strong corrosion resistance. Item Name: Extension Frame Material: Aluminium Alloy Features: Corrosion Resistance, Durable, Easy to Install Size: 9cm x 9cm/3.54" x 3.54" (Approx.) Package Includes: 1 x Extension Frame