Of you purchase a tune your DO NOT need this and this is included in your tune purchase. 
To make tuning more convenient, there's no need to send us your ECU anymore. This OBDII remote tuning device connects to your vehicle, allowing us to flash new C63 ECU tuning software remotely through your laptop. This ensures you get the horsepower and torque you want without the hassle of mailing your ECU. A laptop is required for this remote tuning option. Tune sold seperatly 
Of you purchase a tune your DO NOT need this and this is included in your tune purchase.