Speaker brackets for aftermarket speaker installation. Save time when installing aftermarket speakers. Made specifically for most 5.25"-6"-6.5"-6.75" speakers. Speeds up installation time. Made from high grade plastic for a long lasting secure fit and corrosion resistance. What's Included: For 4 speakers: 1. 2 pairs of speaker adapter (4 brackets). Compatible Vehicles: Made for Chevrolet: 2008-2013 Silverado -Extended Cab models only . Made for GMC: 2008-2013 Sierra -Extended Cab models only