If the magnetic pickup input (green and violet wires) triggers your MSD ignition, the PN 8920 Tach Adapter corrects the operation of most voltage-triggered tachometers that don't read directly off the MSD's tach output terminal. It should also be used with current-triggered tachs wired in series with the ignition switch.Specifications: Brand: MSD Category: Air and Fuel Delivery Product Type: Tach Adapter Sub Category: Fuel Injection System and Related Components Warning: California Proposition 65 Warranty: Manufacturer's Limited 1 Year Warranty Part Number: 8920 FAQWhen do I need the MSD 8920 Tach Adapter?When your MSD ignition is triggered off the magnetic pickup input (green and violet wires).Does the 8920 work with current-triggered tachometers?Yes, it should be used on current-triggered tachs wired in series with the ignition switch.What does the 8920 correct?The operation of voltage-triggered tachometers that don't read directly off the MSD's tach output terminal.{"@context":"https://schema.org","@type":"FAQPage","mainEntity":[{"@type":"Question","name":"When do I need the MSD 8920 Tach Adapter?","acceptedAnswer":{"@type":"Answer","text":"When your MSD ignition is triggered off the magnetic pickup input (green and violet wires)."}},{"@type":"Question","name":"Does the 8920 work with current-triggered tachometers?","acceptedAnswer":{"@type":"Answer","text":"Yes, it should be used on current-triggered tachs wired in series with the ignition switch."}},{"@type":"Question","name":"What does the 8920 correct?","acceptedAnswer":{"@type":"Answer","text":"The operation of voltage-triggered tachometers that don't read directly off the MSD's tach output terminal."}}]}