For some reason the MK220 (and I assume some of other mics) don't come with a proper shockmount. So you have to go buy this one.
Now that said, it's the best shock mount I own. It's very sturdy and has never had that issue of the rubber bands popping out like the other ones I have. It also has excellent rumble rejection, or I've certainly never had issues with it paired with my MK220 (which I frequently use in live recording and drum recording setups). I just wish they'd let you buy the 2 at once. Whose gonna use an LDC without a shock mount anyway?