Big NO. I bought one like that for my Mazda6 several years ago and I didn't like the look. Definitely wouldn't put that on my SLK 55 regardless of price. Go with the flow and proven consensus provided by this forum. The modified R170 is the second best looking, but best performing antenna for the SLK. Available through the SLKWorld Store.
Here is a link to it and with your Paid Membership as a Silver Member you get an additional 5% off at the store. Just PM and I'll provide you with the code to use at checkout if you decide this is what you want to do.