That's what screwfix calls them. Is there another name?

http://www.screwfix.com/prods/16020/...0mm-Pack-of-10

Part 16020.

I need something like that for a curtain rail: machine screw end into
the rail holder and dowel thread into the wall.

Unfortunately the one supplied has about 15mm protruding, which means
that when you deduct 12mm for the plasterboard, 2mm for the plaster,
and 1mm for the paper, there's nothing left to go into the noggin
beneath!

Can I get any longer ones anywhere? Google seems to point me back to
screwfix ;(

TIA