I personally use a Kokkia i10s (not my picture). I've had no problem getting it to pair with headphones, speakers, car. It sometimes takes a moment to actually pair, but that's a minor annoyance to me. The only real down side is the price. It's $67.45 on Amazon. Sometimes you can find it cheaper on eBay, but not often, and usually not more than a few dollars cheaper. Lastly, and as far as I'm aware, it's the smallest external bluetooth adapter for 30 pin. No battery as it's powered by the iPod itself.