Each generation of Apple’s iPhone comes with a mophie juice pack to shore up its battery. Similar to previous versions, the juice pack air for iPhone 4 comes in the form of a case for the smartphone with the case measuring 5.07 x 2.51 x 0.68 inches and adds 2.5oz to the smartphone.

Instead of curvy edges, we have squared off sides resembling the iPhone itself; it has cut-outs for the volume buttons, ringer switch, sleep/ power button, headphone socket and a hole at the back for the camera and the flash.

The bottom edge of the juice air pack has a button and four LEDs to indicate how much battery is left. Recharging is done through the bundled micro USB cable that also charges the iPhone 4 itself and allow it to sync with iTunes in the PC or Mac without removing the iPhone from the juice pack air.

To fit the smartphone, pull of the top edge of the case and slide your iPhone in and then replace the panel.

The juice pack air includes a 1500mAh battery which the company promises can “virtually double” the device talk time to 6 hours of extra 3G talk, 40 hours of audio playback, 10 hours of browsing over the Wi-Fi and video up to 9 hours. This claim can be met when most of the iPhone’s 4 features are disabled during charging. Under normal use conditions, i.e. screen off while charging and Wi-Fi on, the juice pack air added 70% battery life and 40% battery life for a completely discharged iPhone 4.

Mophie Juice Pack Air iPhone 4 has a dedicated power switch allowing the reservation of power for when it is actually needed e.g. when away for a weekend without a charger or in a location where the access of charging power is almost impossible. Simply turn off the power switch overnight to save the power. Smart Battery Technology instructs the iPhone to always drain the juice pack’s battery first.

Summarized Features of Mophine Juice Pack Air iPhone 4

- Virtually doubles the iPhone’s battery life

- The case is strong enough to cover the body of the iPhone from every-day tear and wear nonetheless lustrous enough to uphold the aesthetic of the iPhone.

- Presence of added features for ease of use e.g. four LED lights on the bottom to show how much battery is left

- Power with the flick of a switch where by the use of a built-in stand by switch, one can choose when to activate the juice pack and maximize each battery charge

- Rechargeable Smart Battery hidden inside of a low profile, light weight, soft-touch case

Although the Juice Pack Air for iPhone 4 does the best job of balancing both extra power and a nice case design that looks and feels better even as it provides more energy to the inside, it comes at quite a high price of $79.95.

In addition to that, the design does not come with a screen protector leaving the device’s screen open and vulnerable.