Main Features: 100% brand new High quality hard back cover case for iPhone 4/4S Flash while calling or called Colorful shinning flashOffer complete back protection for your iPhone Power with a CR2016 button cell, included The electron battery can be replaceConveniently to access and removeMade of plastic, very lightweight All iPhone buttons are easily accessible while resting in iPhone 4/4S shell casing
Specifications:Material: Plastic Power: CR2016 (included) Compatible with iPhone 4/4S Product weight: 23 gPackage weight: 50 gProduct size (L x W x H): 11.7 x 6.2 x 1.2 cmPackage size (L x W x H): 18.3 x 9.2 x 1.5 cm

Package Contents: 1 x Sense LED Flash Light Back Case for iPhone 4/4S 1 x 3V CR2016 Electron Battery

Product Note:
You should put the round battery slightly right in the hole before putting on the case. If the case flashes with colorful lights, for about 10 seconds, the flasher protector is workable, and you have positioned the battery in the right place, then the case will flash while you make phone call or being called.