RONHILL Running, Stretch Arm Pocket

My bicep is 30cm when relaxed, and the s/m size is a great fit- tight enough to stop the phone bouncing around while running, but not so tight that it's uncomfortable. I would have given it five stars if there was a seperate pocket for keys etc, but there is only one pocket, so everything goes in together.

I ordered a s/m and I’m an average sized woman. It’s huge! Slides down my arm as soon as I put it on, it’s big enough to fit on my calf! It’s a shame they don’t make them any smaller because the quality is seems good.