I've previously owned the HT820 Bluetooth Headset from Motorola, but now use theMotorola S305 Bluetooth Stereo Headset (Black)[Retail Packaging]for a few reasons. I'll compare the two, in case anyone is trying to decide between different head-sets.I'll preface this by saying that I've used both sets of headphones for 8+ months and am a fan of both: they both do roughly the same job. The biggest difference? How big they are. The S305s are a light, sporty (IE: exercising) and sit nicely on your ears. The HT820s sound great, have great battery life and range.Now let's compare them on a few important features:1) Weight/Battery LifeIt seems the two are tied together. The HT820s weight about twice as much as the S305s but have about a 12 hour battery as opposed to a 6. I find that I can get about 3 days of normal use out of the 305s without charging, so the battery's not so much an issue for me. Now, back to weight: the reason I'm currently using the 305s is that the 820s tended to bother my ears if left in the same location for extended periods of time (the cord that connects them would rest on the same part of the back of my ear for too long). I like the thinner connection of the 305s (even feels better resting around my neck, when not in use).2) Sound QualityThe reason I miss the 820s: superior sound. The 820s have surprisingly good bass and a depth of sound (both devices had slight trouble with certain ranges of sound, mostly high); having bluetooth never left me wanting sound quality. The 305s, on the other hand, have sometimes been quiet, but the problem actually stems from the music file, it just could have been compensated for by the 820s. Over-all? I can easily live with the sound quality from the 305s, unless you're a serious audiophile, I think you could as well.3) ConstructionI've read some other reviewers opinions that the 305s were "flimsy", and I think it's due to the fact the cord is flexible. That's actually a feature, all of the time I've spent with my 305s and I only have one gripe: the foam pad that covers the head-set is nowhere near as helpful for listening as the foam covers that go around the 820s speakers.tl; drSo, to sum it up, I use the 305s every day and won't switch back. The sound quality's good enough, the devices have proven durable (and just as important, comfortable) even for long runs and other physical activity. The battery's great for the device's size, and everything but the ear-screens has stayed well intact.Hope this helps someone find a great pair of head-phones that happen also to take and receive phone calls. :D