hood lock so they cant pop the hood. siren with buildin battery works good, goes off when alarm or cables are cut/disconnect. u cant turn off the siren unless u have the key or just pull the siren from the car and it will still b going off like crazy even out of the car lol. low jack is useless, my friend had low jack in his avalanche. they couldnt find the vahicle using low jack, the police found it a month later without the low jack and stripp. i wish i can get the gps tracking from DEI it will call ur phone / pager/ even email u if ur car is turn on or move and u can track every bit and have full control, turn off, lock unlock doors etc... the point of having clubs, multilock fuel cutoff etc... is too slow them down while the siren goes off and eventually they give up run or straigh to jail. hopefully the thieves get his hands cutoff.