Once the OEM wiper blades are no more, you can install complete wiper blades of your choice. Just make sure the ones you buy have the connection for the XFire wiper arm. These can be the fully integrated versions or the standard wiper blade where you could install wiper refills later on. I install wiper refills every year.

If you want the OEM look back, then go to a M-B parts website, and purchase OEM wiper blades for the R170 SLK320 series. Then you can buy just wiper refills when you need to change the wipers out. You'll end up getting wiper blades with the spoiler integrated on both blades. The XFire actually only had the spoiler on the DS blade. The PS didn't come with the spoiler. Not a big deal either way - MHO. I think Valeo supplied the wiper blades for the XFire.

You'll also notice that on my Amazon receipt attached in an above posting, the wiper refills were different lengths for DS & PS. Putting the same size wiper blade on both sides may not be an issue. For all I know, the wiper blades from M-B for the R170 SLK may be only 21" long, which should work for both sides. Others can chime in on this that have specific experience purchasing M-B wiper blades. Just saying before I bought 2 wiper blades of same size from a M-B website, I'd be sure the PS fits properly & doesn't rub the windshield trim surround..

07/26/2020 - After sleeping on this feedback, I'd probably only buy the M-B wiper blade for the DS. Then I could purchase a wiper blade (21" long) of similar design from another supplier for the PS. That would give me the OEM Crossfire setup.