I used to know what this was but I cant remember anymore, i'm thinking alarm system or horn but i could be way off? Its supposed to be bolted below the fusebox but I relocated it up there cause the bolt was somehow broken off in the hole its supposed to goto from the previous owner. Well me not thinking ahead it rubbed against the sharp aluminum and popped the am2 fusible link shutting down my ecu. I just unplugged it and I havent noticed a difference so it cant be that important.