DESCRIPTION: COMPATIBILITY: The electrical alternator diode compatible with Chevrolet Gmc Hummer Pontiac. REPLACE PART NUMBER: 12135037. FUNCTION. The voltage will be lower than expected when upgrading the battery to AGM battery, because AGM battery requires higher voltage than lead-acid battery to charge, and your alternator output power is insufficient. In this case, you will need this 12135037 multi-function diode to provide enough power output to solve the above problems well. PACKAGE INCLUDED: 4 pcs Multi-Function Diodes