I'm a firm believer in supporting our Crossfire Vendors as they provide a valuable support service to our marque. If the price difference between one of our preferred vendors & another source is 10-15%, I'll buy from our preferred vendor. But in this case, there are considerably less costly (35%) alternatives to the kit provided by Needswings (sorry Rob). Now, the kits aren't exactly the same as Rob provides a couple of additional parts, but the kit listed on Amazon is worth looking at.

2001-20014 SLK320 5-Speed AutoStick Transmission Service Kit

And Ravenol is listed as a certified (tested & approved) transmission fluid meeting M-B's 236.10 specification. Interesting that Ravenol is shown on the label as a Semi-Synthetic fluid.