This is the Axxess AXRC-GM1 | GMRC-01 radio replacement interface/chime module.
The Metra AXRC-GM1 | GMRC-01
is designed to be used in a non-amplified GM vehicle or in vehicles where the OEM Amplifier has been bypassed (OnStar will not be retained). This harness retains all the factory warning chimes that would be lost when the OEM radio is removed. It also provides a 3 Amp 12 volt switched accessory for proper radio operation and retain the RAP feature if equipped.