These Classic Instruments speed pulse sensors and their adapters enable you to calibrate your speedometer in less than a minute, and you don't even have to leave your driveway! Each and every Classic Instruments product is designed and calibrated in-house to ensure quality and dependability with one goal in mind--to meet the unique needs of all automotive enthusiasts. When it comes to speed pulse sensors, adapters, and all other instrument products, there's no better place to go than Classic Instruments.