Square black heavy duty OBDII cable for the PT30 ELD electronic logging device. For Mack and Volvo trucks. Important note: HOS App Service is not required, it is 100% optional to use our service; but if you need it, this is what we offer: HOS App for $39 to $45 paid monthly. If you prepay 6 months you get reimbursed the full cost of the device and the cable. Yes, this option makes devices and cables free of charge. Additional Details ------------------------------ Product description: Square black heavy duty OBDII cable for the PT30 ELD electronic logging device. For Mack and Volvo trucks. Important note: HOS App Service is not required, it is 100% optional to use our service; but if you need it, this is what we offer: HOS App for $39 to $45 paid monthly. If you prepay 6 months you get reimbursed the full cost of the device and the cable. Yes, this option makes devices and cables free of charge.