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. 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 or 2.17" x 1.58" (approx.) 2: 5.7cm x 4.3cm or 2.24" x 1.69" (approx.) 4: 5.7cm x 3.5cm or 2.24" x 1.38" (approx.) 12: 5.1cm x 3cm or 2.01" x 1.18" (approx.) 21: 5.2cm x 2.8cm or 2.05" x 1.10" (approx.) 34: 6.2cm x 3.9cm or 2.44" x 1.54" (approx.) 36: 6cm x 4cm or 2.36" x 1.58" (approx.) Package Includes: 1x Rear Derailleur. 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! Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.