Fixed position block is manufactured by LBTEK from 6061-T6 aluminum alloy with a black anodized surface finish. The fixed block is used to calibrate the position of mounting posts or square bases, facilitating realignment when these components are removed from optical systems. The three marking points on the fixed block indicate contact points for square components, while the two outer-arm marking points can mark contact points for post-type components. This fixed block can be secured either with screws or using the CB-2 clamping fork, making it suitable for situations where the fixed block cannot be directly mounted on tables tapped holes. Note: The fillet radius at the right-angle corners of square components must be less than R1.5. For square bases with fillet radii greater than R1.5 but less than R10, two fixed position plates should be used for positioning.