Well I got the part from the link below and it was too big despite them saying it fits.

SC-4980J

Hi-Hat Seat

Fits Gibraltar and most professional hi-hat stands with 1" to 5/8" tube.

The inner diameter of the piece is 3/4". There were no double diameter options as described above by zenstat. My pipe is 5/8" OD. I made it work by rapping the correct about of black electrical tape to bring out the diameter and make it fit snug. Looks good, well made piece.

Wish it fit without correction but i'm happy.

That's odd. I got mine some years back so maybe it was a different model -- or they have changed the specs. Glad it worked out for you anyway.

In the meantime I updated my original diagram because when I went back and had a closer look (with calipers in hand) the method for accommodating two different tube sizes was a little different from what I had illustrated.

They need to update their specs about this piece then. Sorry that I steered you in the wrong direction but glad you were able to make it work. Perhaps if that one had still been in that store a few years back I would have known that it wasn't going to fit perfectly. This still may have been about your only option as far as an aftermarket replacement. Possibly Cannon sells one that's slightly different but that would be tougher to find.

Another option would be to find the whole top tube of a Ludwig hi-hat (1123-1 or 1124) which will have a metal plate integrated with the top tube in place of a separate rubber or plastic cup. These stands use a nylon bushing to guide the pull rod which can fall out or wear away. Those are no longer available either, but I've created a work-around.

No worries, it worked out well. They advertise it to fit 5/8"-1" tubes, they must of changed the part design.