Master Lock 4841DATSEN Auto Sentry Wireless Anti-Theft Vehicle Alarm System Detects shock, glass break, and voltage drop, Siren mounts anywhere under the hood with double-sided tape Alarm attaches to battery terminal and sensor plugs into VPA or accessory socket Protects your vehicle and its contents, pressure sensor detects unauthorized vehicle entry into passenger compartment of cars and trucks Installs easily in minutes with no tools or splicing, no wires to cut 110 decibel alarm siren and includes 2 fobs