We felt the earpiece fit quite securely when placed in the ear, but if you want additional security, you can also use the optional ear hook. The hook is thin, flexible, and can rotate to fit either the left or right ear.
Underneath the earpiece, at the very tip, you'll find a small rubber nub. This is essentially the part that helps the HX1 with bone conduction. When placed in the ear, this "stealth mode" sensor will sense the vibration of your jaw as you talk, and then translate that into speech for the other person on the line. Near the bottom of the headset is another microphone, which is used to amplify your voice, and right next to it is a LED indicator light.
Features of the Motorola Endeavor HX1 include the typical answering, ending, and rejecting calls, call waiting support, call mute, last number redial, the capability to transfer calls from the headset to the phone and vice versa, plus multipoint support. The latter means that the HX1 is able to connect to two devices at the same time. This works especially if you want to use one headset with two phones. The first phone to pair and connect to the HX1 will be designated Phone 1, the second one will be called Phone 2.
We paired the Motorola Endeavor HX1 with both the Apple iPhone 3G and the . The Endeavor HX1 features voice prompts similar to the BlueAnt Q1--it announces to you when it's ready for pairing and walks you through the pairing process. It will also announce its battery status, when stealth mode is on or off, and if an incoming call is coming from Phone 1 or Phone 2. We found the voice prompts handy, especially when handling more than one phone.
We were extremely impressed by the sound quality of the headset overall. On our end, we could hear our callers very clearly with plenty of volume, though we did hear the occasional static and crackle. It was about on par with the incoming call quality of the handsets.
As for outgoing call quality, we found that we didn't have to use the "stealth mode" bone conduction all the time, especially in a quiet office or a moderately busy restaurant--the dual-microphone noise-canceling CrystalTalk technology was sufficient for the most part. With just CrystalTalk and without activating "stealth mode," callers said we sounded very clear with a natural sounding voice. They didn't hear a lot of static or interference. However, callers could still hear some background sound at times when we were outside, and the HX1 did poorly with wind noise when just using CrystalTalk.
It was a whole different story with the "stealth mode" activated. Background noise was absolutely eliminated--even when we were standing in front of a fan blowing at full speed, our callers didn't hear the fan at all. However, while they did say the sound quality improved, we did encounter a few snags. They said our voice sounded digitized and almost garbled at times. We had to enunciate words and speak a bit slowly and deliberately to avoid sounding garbled or mumbled. Our callers also heard a tiny bit of crackling at times. This is why we would only use "stealth mode" in the most extreme of noisy situations, since the bone conduction affects the quality of the voice.
The Motorola Endeavor HX1 has a rated talk time of 7 hours talk time and 10 days standby time.