I don't seem to be able to find GT2 pulleys for sale which have a 6 mm bore (hole) to put on my 6mm shaft.
I see only 6.35 mm GT2 pulleys on eBay. The ones that listed as 6mm turned out to be 6.35mm after I contacted the sellers to make sure.

So is that normal? I need to use a 6.35 mm bore GT2 pulley?
Or is a 6.0 mm bore GT2 pulley (20T) just rare?