This is a GM LAN retained accessory interface for certain 04-09 GM vehicles.  You need this interface to retain the door chime, give you switched power, and keep LAN communication intact for certain OE features when installing an aftermarket radio.  Compatible vehicles are listed on package, but may work with others.  

Item is brand new and unopened. Pictures of item is what you will receive.  PayPal only, please.  Sold as is, no warranty.  Will ship within 24hrs of payment. 

Thanks and God bless!