Features: Bicycles Rear Derailleur Chain Gaps Adjustment Gauge Tool. Make of ABS materials, enduring and practical to use. Special tool for adjusting the rear derailleur. The clear scale on this tool, easy to accurately adjust the chain Gaps, allowing you to use this tool easily. Light weight and portable, perfect for adjustments or maintenance at homes. Specifications: Materials: ABS Size: about 15.5x7.8cm/6.1x3.07inch Package Includes: 1pc Chain Gaps Adjustment Tool note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.