Features: brand new and high quality Fine workmanship and precision cnc machining do not make easy to deform and wear resistant, and it has high hardness. The surface anodizing treatment makes it scratch resistant, corrosion resistant and bright colors. Made of aluminum alloy material, the product is durable. There are many models to satisfy your requierment. It is suitable for cycling,professional and durable,you deserve it. Package Includes: 1x Rear Derailleur. Specifications: Item Name: Rear Gear Hook Material: Aluminum Alloy Attributes: 1, 2, 4, 12, 21, 34, 36 Features: solid, cnc precision machining, anti-oxidation Size Details: 1: 5.5cm x 4cm/ 2.17" x 1.58" (approx.) 2: 5.7cm x 4.3cm/2.24" x 1.69" (approx.) 4: 5.7cm x 3.5cm/2.24" x 1.38" (approx.) 12: 5.1cm x 3cm/2.01" x 1.18" (approx.) 21: 5.2cm x 2.8cm/2.05" x 1.10" (approx.) 34: 6.2cm x 3.9cm/2.44" x 1.54" (approx.) 36: 6cm x 4cm/2.36" x 1.58" (approx.) note: 1, 2, and 12 rear derailleur hanger can be used only if they have the same shape. No. 36 rear derailleur hanger is for MERIDA300, 350, 360, 500, 550, 600, 650, 700, etc. Please allow 0-1cm error due to manual measurement. Make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!