I just tried the Flipbelt out on a run for the first time and am so happy with it. I had no trouble at all fitting my iPhone 7 Plus while in its Speck case (with a Popsocket on). There was no struggle whatsoever.

 I love that there is more room to stash other things if needed, such as keys, money, etc. There are four slots total.

During the run, it was secure, and I didn't notice it was there. No bouncing or bulky feeling.

It's a great solution for me because armbands no longer feel comfortable now that I have a bigger phone, and I love that I can leave it in the case.