borg helical focuser (look at the hutech site for details. Apparently I can't post a URL or I would post it here).
In addition, I had a custom made adaptor that screws onto the borg part. The adaptor will fit inside a tube 84mm to 85mm diameter (I had it orginally attached to a apogee 90mm widestar scope). The helical focuser can also supposedly fit on the back of some sct's and mak's.
I accept paypal, money order and check (check waits for clear). $90 including shipping within the continental US.