Ha Ha,
That is a trap for young players. The Pentax Japan website has been like that for several years. I think the problem comes about with the "English" interface on that website. Those 4 eyepieces are listed on the English version of the Jap website as "spotting scope" eyepieces. No where will you find a link to "Astronomical eyepieces".
Unless of course you can read Japanese
If you go to the Japanese version of the website and go to the "eyepieces" page, you will see all focal lengths listed. Whilst you probably can't read the writing, you can at least read all the relevant numbers.
http://www.pentax.co.jp/japan/produc...escope/eye/xw/
Therein is your answer gentleman and unfortunately Rob your 3.5mm XW isn't worth one thousand of anything
Cheers,
John B