Kit details: 4 SBR20 linear guide limiters; our linear stop bushings securely fix your axis and position it precisely. With an inner diameter of 20 mm and an outer diameter of 40 mm, they are perfectly suited to your needs. Stable holding force: our unique set screw design ensures increased holding force, especially if the shaft material is softer than the set screw material. You can count on reliable and safe fixation. HIGH QUALITY MATERIAL: This linear guide limiter is made of aluminum alloy. It is corrosion-resistant, high-strength and wear-resistant. In addition, it is easy to install and maintenance-free. EASY INSTALLATION: The clip-on wave rings are designed for quick installation in large openings. They are firmly fixed and do not come off easily. The shaft is clamped firmly without being damaged. APPLICATION: Suitable for installation on various machines, such as: engrave, woodworking machine, printing machine, DIY CNC milling machine, 3D printer.