Over a year ago, Televue ceased production and I gave up trying to get these for my 35mm panoptic (and perhaps the 27mm).
But, THEY'RE BACK - new and improved, apparently!
http://www.televue.com/engine/TV3_page.asp?id=158
"EGE-0020 Eyeguard Extender, twist-on style"
OPT have just sold me two at USD25 each and USD11 for el-cheapo ("good luck if they ever turn up") shipping. (next step up was USD33 for shipping - nope!)