Features: 1) Shows SIM1 or SIM2 number on screen 2) Both numbers can be on active at the same time 3) Select a mobile number straight online in the STK menu, without needing to turn the phone off / on 4) Saves charges on roaming and long-distance calls 5) No data loss when switching 2 numbers or turning on / off 6) Protects SIM card against loss and damage 7) No need to cut the card and change covers 8) Suitable for almost all GSM mobile phones 9) Six month guarantee (man-made faults and neglect of use are not covered in the guarantee)