Programming: DIY: Just a DIY programmer with Installation instructions at home instead of finding a locksmith0r car dealership. You only need your existing working key with a new key fob and OBD2 Car Key Programmer Tool. Only factory Originally features will work, Will not add new functions to your vehicle. Note: Our products will be carefully inspected to ensure they can work normally. Our products are aftermarket parts instead of old ones. They can work normally as long as the compatibility, part number, size, and appearance are consistent with the old ones. Every vehicle can only program up to 4 key fobs. Before programming, you must keep your old working keys to start the engine and install it. it's only for vehicles0riginally equipped with keyless entry. Must be strictly read and refer to the steps of the manual for programming, the time interval between instructions is limited, can not be too long operation. Each programmer can only be used for the vehicle it was originally programmed for and cannot be used on other vehicles. This is a non-OEM product, accessory only! Fitment: for Hyundai Elantra Sedan 2011-2016. How to replace the battery? Take out the key and use the tip of a very small screwdriver as a tool to open the back case, replace the same battery carefully. You can use a clean cloth to clean the battery in case some dushes exist. Package Included: 1 Pcs OBD2 Car Key Programmer Tool, 1 Pcs Keyless Entry Remote (Battery included), 1 Pcs Key Chain, 1 Pcs Installation Instructions.