For some time now, the guys over at Mophie have been producing some great iPhone cases. Not only do Mophie’s “Juice Packs” protect your iDevice while appearing easy on the eyes; they also include built-in batteries, which extend the lifespan of your iPhone 3G, 3GS, and 4. And, now, Mophie has a new battery case on the way. It’s called the “Juice Pack Plus,” and it promises to double the battery life of your iPhone 4.

As the guys over at Gizmodo note, the iPhone 4 is already a pretty juicy device. However, certain things will always burn away at your handset’s battery – especially since HD video recording and other power intensive features are included in Apple’s latest handset.

Thankfully, there is now a way for your iPhone 4 to live through the day, and beyond. As Mophie notes:

This ultimate iPhone 4 power user accessory more than doubles the battery power of your iPhone and provides the complete protection of a soft-touch case and shock-proof band.

While the above image notes that the product is “coming soon,” over at Mophie’s site, you can order your own Juice Pack Plus right now for $99.95. The product, which looks pretty snazzy (and Bumper-esq, don’t you think?) is definitely worth checking out.

Take a look at Mophie’s site, and decide for yourself. If you have an opinion on the Juice Pack line, let us know in the comments below.