Features: Quickly and easily level your optics in the outdoor, at ranges, or at home. Convenient storage and transport, Great for long ranges shootings, perfect level. Suitable for 20mm/11mm leads rail, can installed quickly and easily for rail. Use this bubble level to make surely your rifles level shootings the targets. Mounts quickly and easily to the rifles scope tube. Specifications: Materials: Aluminum alloys Clamping Size: 20mm(0.79inch)/11mm(0.43inch) Package Includes: 1pc Scope Bubble Level 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. 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.