Approach to clearing old codes: Long press the upper two (A & B) buttons to clear old codes(The LED indicator will flash three times, followed by a continuous fast blinking, which is the sign of cleared state.). Approach to duplicating: Place them side by side(as close as possible), then press both one key of your old remote and the to-be- key on this remote simultaneously. The LED indicator will flash about three times, followed by a continuous fast blinking. Learning process done. Other keys accordingly. Approach to recovering: Press the lower two buttons (C & D) for about 3 seconds till the light is on and flicker. (Or you can delete the codes and repeat the learning process. Approach to test if the old codes are totally cleared: Press any key on the remote duplicator, if the LED indicator blinks instead of being on, codes cleared. Otherwise, undone. Humanized design: Button slide cover to protect buttons from accidental unplanned operation. Application: Vehicle central locking systems, garage doors, electronic doors, car sunroofs, heating systems, etc. Specification: Material: ABS plastic Working Voltage: DC12V /27A Woring Current: 12mA Operating Frequency: 315MHz Control distance: 50-100m / 54.5-109 Yard (in empty areas) Overall Size: ( L x W x Dia. ): 67 x 35 x 10mm / 2.63 x 1.37 x 0.4 Inch Color: as shown in the display pictures Package Includes: 1 Piece Garage Remote Control