ProCal SNAP for JL Wrangler and Gladiator truck is the latest addition to AEVs growing family of electronic calibration modules. This cost effective calibration module will accurately correct your speedometer after installing larger tires (up to 42 tall) and/or changing the axle/transfer case gear ratio, saving you from the headaches of going to the dealership or depending on a lesser quality module. After installing AEVs Programming Harness (included), ProCal SNAP simply plugs into your vehicles OBDII diagnostic port and interfaces with the user through the audio system equalizer. After inputting the necessary numerical values for the tire size or gear ratio through the audio equalizer (example: 35.5 tall tire = bass 3, mid 5 and treble 5) the settings are saved by pressing and holding a combination of buttons on the steering wheel. Its that easyin fact, some might say its a SNAP! Please note: ProCal SNAP is included with AEV JL suspension systems!Additionally, all AC-level ProCal SNAPs now feature TPMS functionality!