The Richter Optica S6-EYE stereo microscope eyepieces (paired) have a 30mm diameter and are made for use with the S6 stereo zoom microscopes. Three magnifications are available:

S6EYE-10x: Widefield, high-eyepoint 10x eyepieces / 20mm field of view (accepts 24mm diameter reticle)

S6EYE-15x: Widefield, high-eyepoint 15x eyepieces / 15mm field of view (accepts 24mm diameter reticle)

S6EYE-20x: Widefield, high-eyepoint 20x eyepieces / 10mm field of view