New-Old-Stock Replacement Rubber Folding Eyecups for Zeiss Classic 8x20B and 10x25B Mini Binoculars. These are the binocular models that fold like a "Z". These eyecups thread onto your binoculars, and you can use them with these replacement sleeve, or your original sleeves. Outside male thread diameter where the eyecups thread onto the sleeves is 22.90mm. Thread pitch at the same place is 0.75mm/thread. Easy replacement. Hard to find, it seems. Ask me if you're uncertain about the applicability to your glass. I'll try to help you.