"Doc" <docsavage20@yahoo.com> wrote in message
news:f0c1bc20.0308191026.346846dd@posting.google.c om...

The stated size is the diameter of the nominal eyepiece-focuser interface
(a circle). The focus is allowed to be a bit larger than this diameter,
and the eyepieces are to be a bit less in diameter. That way all 1.25"
eyepieces will fit inside all 1.25" focusers, even allowing for variations
in
machining tolerance.

Cheers,
Larry G.