As I said, the Pump is an in-ear headphone and the tips are designed to be really jammed in your ears to get a tight seal. You get various eartips, including a foam set that allows more sound in so you can hear traffic around you when you're running or biking, and one size should work for you.
On a more critical note, I thought the Pump's sound was only so-so for a wireless Bluetooth headphone. If you get a tight seal, there's plenty of bass, but the headphone just doesn't sound clear or refined -- at all. I also noticed a very faint background hiss in quieter environments when I wasn't listening to music (I could hear it when I first turned on the headphones).
Perhaps because the box promises crystal-clear "HD" sound, I expected more (and certainly more clarity), but overall I found the sound more in line with what a $20 wired headphone produces. Some people may like that bass push, but I need more detail.
I was OK with the sound for workouts but I personally would not use this headphone outside of sports activities. The similarly priced JayBird BlueBuds X sounds better and so does the $130 Plantronics BackBeat Fit. However, that Plantronics model has an open design (so you can hear traffic) and lets in a lot more ambient noise.
The Pump plays louder but the BackBeat Fit has more natural, better balanced sound, is lighter and arguably a little more comfortable. I would be more inclined to use the Plantronics for daily use.
The Plantronics does have one small downside: the cord bounces up and down a bit. The cord on the Pump is a bit stiffer and moves much less. The Pump also comes with a little clip that allows you to adjust the cord's length (shortening it will prevent any bouncing), which is a nice bonus, and Plantronics should have included one.
While the Pump fell short on the sound quality front for me, from a design standpoint it's an appealing wireless sports headphone that should work well for a lot of people. Like the Plantronics BackBeat Fit, it ideally would cost a little less than its list price of $130. But hopefully it will come down in price over time.