2" star diagonal with 99% reflection

The Castell star diagonal has dielectric coating, providing 99% reflectivity with much longer lifetime than normal or enhanced coatings. The mirror surface has only L/10 ptv error, which is really smooth, resulting in excellent image quality. The brass compression ring protects the eyepieces. The set including a 2"-1,25" adapter with a 2" filter thread on the back side.