Docooler Qi Standard Wireless Charging Receiver for Samsung Galaxy S4 i9500 / i9505 - Black Ultrathin design, compact and light weight without increasing additional weight of the S4. Adding wireless charging feature by piggybacking it on the battery of S4, it works well with any Qi-enabled charger. The receiver can be attached to the the battery all the time, and it would not interrupt the normal use of the S4. It is specially designed for Samsung Galaxy S4. Easy to use, Take off the back cover, attach the Energy Card on the battery, put on the back cover.