the wording on this listing is confusing the hell out of me.
i'm hoping it means it's designed to fit into 1" head tubes, but use 1 1/8" threadless stems, correct?

https://cgi.ebay.com/Profile-Stem-Ada...QQcmdZViewItem

That's who I am reading it.

this whole part
"* Quill Insertion Diameter: 25.4mm for 1 1/8" stems and 22.2 for 1" stems
* Steerer Clamp OD 25.4mm, for 1", 28.6mm for 1-1/8"

is just confusing me.

Ack! stay away from bikestop. Not that I love Nashbar or anything, but you can get that from them. you can get that from anyone.

any particular reason?

i liked this one, cause it (seems to be) made for 1" tubes, but 1 1/8" stems, which, from what i've looked at, gives me a lot more options.

how is stem length measured? as in, from which point to which point?

You can definitely find that other places. I have purchased things from BikeStop before though, not any real troubles, they are just a bit slow.

Nashbar has one.

Perfomance has one, albeit a bit more pricey.

I am sure there are many other good sources.

Stem length is from the centre of the steerer to the centre of the bars, measured along the axis of the stem. (At least that's what I think)

The confusing part is probably an error. The title says that it fits into 1" threaded forks and gives 1 1/8 threadless stems something to grab.

I'd stay away from it, though. Ugliest, heaviest, most complex and vulnerable stem setup ever.

It is a stem quill that measures 1" you fit it into your fork/steerer tube and the you can use 1-1/8" a-head style stems instead of...1" quill stems
Stems are usually measured center to center. And length will be refered to in mm's or cm, I.E if you see a stem listing that say length of 11 it is 110mm or 11cm.

cool, thanks.
im not hell bent on a threadless stem, but i hate stems that you have to take the tape off in order to remove the bars, and very few quill stems have removeable faces.