Microscope Eyepiece Adapter from 30.5mm to 23.2mm
Eyepiece Adapter for Microscopes with outer diameter 30.5mm and inner diameter 23.3mm (to allow 23.2mm eyepieces
Length of nosepiece: 26mm
Diameter of nosepice: 30.5mm
Optical length: that's a good question... 2.1mm is the thickness of that obstructing part on the outside that goes around, but there is also a 6mm deepening inside that will most likely let the eyepiece go deeper...
(The picture shows an earlier model...the new model is slightly different, but the basic idea is the same)
Overall length: 28mm