Are you talking front or rear?
Also why do you want to?
Not sure about the arms themselves mate, but I changed the blades on my old Zetec S to the smooth type and loved the upgrade. Under a tenner off the bay, better wipe, and looked a lot smoother and cleaner than the old ones.
Always look for the Aero style blades, they are definitely worth it!
Yeah, lovely little cheap upgrade, much more modern. Just searched ebay and here's the first result, £7 posted.
Need to stress I have no experience of these exact ones, so you might wanna research yourself before you decide. You can always get branded ones for a lot more, but I used cheap ones and got them for my da, bro and girlfriend's cars and they all couldn't fault them.