Best Iphone 4 Battery Extender Case

iphone 4
The iPhone 4 is a slate smartphone designed and developed by Apple. It is the fourth generation of iPhone, and successor to the iPhone 3GS.

extender
A person or thing that extends something
A substance added to a product such as paint, ink, or glue, to dilute its color or increase its bulk
In set theory, an extender is a set which represents an elementary embedding having large cardinal properties. A nonprincipal ultrafilter is the most basic case of an extender.
(Extenders) Low cost materials used to dilute or extend high cost resins without much lessening of properties.
Any of various substances designed to extend any of several properties of a material; Any of various components designed to extend the length of a device; Another term for runner or quick-draw. (from sense #2)

battery
A container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power
An artillery subunit of guns, men, and vehicles
a device that produces electricity; may have several primary or secondary cells arranged in parallel or series
A fortified emplacement for heavy guns
a collection of related things intended for use together; "took a battery of achievement tests"
group of guns or missile launchers operated together at one place

case
an occurrence of something; "it was a case of bad judgment"; "another instance occurred yesterday"; "but there is always the famous example of the Smiths"
look over, usually with the intention to rob; "They men cased the housed"
encase: enclose in, or as if in, a case; "my feet were encased in mud"
An instance of a particular situation; an example of something occurring
The situation affecting or relating to a particular person or thing; one's circumstances or position
An incident or set of circumstances under police investigation