According to the Mophie ”Need even more battery power for your iPhone 4? The mophie juice pack plus has our largest juice pack battery which extends the battery life of your iPhone for hours! The juice pack plus also provides a comfortable ergonomic design with the complete protection of a dual-injected hard shell case with protective rubberized band. Since it is designed to more than double the time you have to Rock, Talk, Surf and Send with your iPhone 4, the mophie juice pack plus is the ultimate iPhone 4 battery case for travel or business”.Right now the Mophie Juice Pack Plus charging case is available with a price tag of 99.95$ on mophie store.
Source : mophie