Note: I received this to try via Tomoson.com no other compensation was provided. These options reflect my own expereinces.
I have had the hardest time finding a holder for my phone that fits around my arm. I have bigger arms in particular so they tend to either cut me off, or just in general are not a good fit. On top of this with a Windows Phone you have to find something that fits another phone that will work.
I got the chance to try the i2 band which is for Iphones. A lot of Iphone products work for Windows phone, but I still was skeptical.
What I like about this is it fits well on the arm without feeling like its cutting me off. It does not bounce which has been a challenge for me for some phones. There is also a place that you can stash a credit card (if you throw it behind the phone. It kept my phone cozy and safe while I run. There is also reflective material which makes it good for the dark rain. Also, its really good for my bike time. It stays put and does not move.
The only downside I have and for me this is a big one, is the key holder. The key holder is smaller then you would ever expect and does not fit any of my keys which means I am still keeping my keys on me when I run. But in the long run it still does not keep it from being a good answer to the need of a good phone holder.
This is a great option for runners who are looking for a good fit to keep their phone safe.
You may check it out here Best Running Armband