I went on several runs with them and they stayed in my ears without a problem and kept their tight seal. The only issue for some people will be that the noise isolation is so good (particularly with the USA model) that very little sound from the outside world is let in. I ran against traffic on a country road, so I could mostly see cars coming, but on a couple of hills where I couldn't see over the other side, I had to stay on alert because there was almost no shoulder to the road and I couldn't hear cars until they were about 10 yards away.
All the iSport models have an L-shaped plug, which is typically more durable than a standard straight plug. However, it's worth mentioning that if you have a thicker "tough" case on your phone you might have some trouble getting the plug to fit into the phone's recessed headphone jack.
On a positive note, I appreciated the protective spring-clasp pouch that's included with the headphones. Monster ships the same pouch with other earbuds and I consider it one of the best protective cases on the market because it offers decent protection but isn't bulky at all. It's also easy to get the earphones in and out of.
As for the integrated ControlTalk microphone, (t's compatible with most recent iOS products, but check this list to see whether it's compatible with your smartphone. I found it worked well for making calls. Interestingly, the standard iSport Immersion has volume controls on the remote while the step-up USA doesn't. As with all ControlTalk remotes, there are no transport controls per se. You simply simply tap the answer/end (pause) button twice to skip a track forward and tap it three times to skip back. Since it's easy to skip forward but more challenging to go back, this won't be the ideal remote for some folks.
Overall, I really liked the Monster iSport Immersion headphones. As I said in the intro, I consider them to be among the best wired sports in-ear headphones available and I wouldn't hesitate to use these on a day-to-day basis. While they won't fit everybody equally well, I got a very secure fit and they stayed in my ears on all my 4-mile "test" runs. They fit more securely than the
I was able to get a slightly tighter seal with the limited-edition USA model, which helped augment the bass a bit, but I can't say it's worth spending the extra money on that model. For most people the standard iSport Immersion will be fine. While it may offer too much noise isolation for some, I recommend it to anyone looking for in-ear sports headphones with a secure fit and premium sound. They're great for the treadmill or elliptical machine at the gym and will also stay in your ears when you hit the road outside.