Let me preface this by saying that I have never used an M5, so I am working off of educated assumptions.
I do believe that I have an answer for you. This is how I would do it, anyhow: sweatbands
I assume that the M5 may be larger than one sweatband. Simple solution: keep two sweatbands on one wrist. This is a common style (at least among people within and below my age range), and so it should not arouse suspicion. Skate companies typically have a very nice assortment of stylish wristbands. If you choose to venture down this path, you run the risk of being labled a poser by those in the skate culture, so you may want to learn to skate this summer as well. ☺
Here is a nice pair as an example: http://www.ebay.com/itm/Zero-Skateboard ... 0639358799