This scope mount bubble leveler is compatible with any 20mm rail series. The scope bubble leveling rail is made of strong and sturdy metal that is not easy to be damaged or worn out. The scope leveling rail is convenient to install and use, no need to use any special tools. The scope mount leveler fine workmanship and is smooth and fine, comfortable to use. The bubble leveler is a good tool to level the rail, and is a good choice to replace the worn or damaged. Specification: Material: Metal. Color: Show as picture. Size: Length: 53mm, diameter: 10mm. There might be a bit color distortions due to different computer resolutions. There might be a slight errors due to different hand measurement. 1x Bubble leveler. This scope mount bubble leveler is compatible with any 20mm rail series. The scope bubble leveling rail is made of strong and sturdy metal that is not easy to be damaged or worn out. The scope leveling rail is convenient to install and use, no need to use any special tools. The scope mount leveler features fine workmanship and is smooth and fine, comfortable to use. The bubble leveler is a good tool to level the rail, and is a good choice to replace the worn or damaged.