To clarify amx 1397 post; his link to a bolt kit (the one in red) is not the correct kit for our cars. He has tried to edit with the correct eccentric kit number (written in black) but that did not work for me. If you go to ebay do a search for Mercedes eccentric bolts W170 or W202 and the correct eccentric bolt kit should be found with the Mercedes number 202 330 01 18. The simpler route is to just go to Needswings and purchase from him and you will have the correct kit.
I too fail to see the value of the adjustable K-Mac kit for 99% of us. If you are just concerned with the front tires wearing out unevenly then the eccentric bolts are the easiest and least expensive fix. If you race your car on a road course or track then there may be some advantage to the adjustable bolts, but you spend a lot of time and rubber finding the correct setup for each track.