A message on the front of the manual for BlueAnt's Pump HD Sportsbuds wireless Bluetooth headphones reads: "The best possible sound comes from the best possible fit."
With bona fide in-ear headphones like the Pump, that's true, because if you don't get a tight seal you lose a lot of bass. To help you get that tight seal, BlueAnt includes a couple of optional stabilizers that snap onto the buds. Ostensibly, the stabilizers are there to help "lock the Pump in place" when doing more extreme activities, but I couldn't get a tight seal without using them.
The stabilizer design works well overall, and these headphones really stay in your ears (they didn't move around at all when I used them on a treadmill and elliptical machine in the gym) and should provide a comfortable, secure fit for most people, which is the most important when it comes to wireless sports headphones.
That said, I did find that at times that the stabilizer dug into my ear a little, and it would have been nice if BlueAnt offered different sizes of stabilizers and perhaps made them out of slightly less rigid rubber. If you're lucky, you won't encounter this issue, and some people will be able to get a tight seal and secure fit without using the stabilizers.
The headphones do seem durable and are waterproof. In fact, if you have all the ports closed off -- a rubber gasket covers the Micro-USB charging port -- you can literally put them under the faucet and rinse them off.
While Bluetooth doesn't transmit underwater, the other thing you could do is wear these in the pool if you keep your head above water. They have up to a 100-foot range, which is more than the typical 30 feet that Bluetooth offers, and battery life is decent enough at around 8 hours.
The headphone's housing has a nice, soft-to-touch feel to its finish, and the controls are well placed in the right earpiece and can be operated blindly. The play/pause button doubles as an answer/end button and the volume controls double as transport controls, allowing you to skip tracks forward and back by double tapping them. A microphone is built into the unit, which allows you to use this as a stereo headset for making cell-phone calls. (This Pump is designed to work with iOS devices, so the remote functionality may not work with all phones, but the microphone will).