Avital 4105L Avistart Remote Start with Two 4-Button Controls Virtual Tack; dedicated A-to-D converter samples your vehicles voltage hundreds of times each second, eliminating the need for a tachometer wire connection D2D serial data port Quickly connects your Avital system to other interface devices via D2D cable XCR onboard relays Extreme capacity remote start relays are built-in to Avital remote start systems.