Your car lock is not enough , also GPS system can only be a tracker after your car is stolen , so you need this smart system to help you stop the theft during or after it happen. More functions please see below : 1.Anti-theft :Itll dial the preset tel No. or send SMS when a car theft happen, light&siren can be choosed at the same time. 2.Anti-rob:when a robbery happen, driver can press the emergent button to call the preset tel No., the call receiver can hear the sound , shout at the robber, and stop the car power or gasoline so that robber cant drive. 3.Faraway control by telephone with password . 4.Wireless hands free telephone in car, assure safe drive . 5.Auto remind driver after 10 secs. to arm the car if he/she forget to arm. 6.Auto remind driver whether the car is in GSM web service range. 7.Can exactly know from mobile phone SMS or web where is the car . 8.Only need mobile phone SIM card to support , no need extra service fee .