The MAD HB Drone Arm Set is specifically designed for large multi-rotor/e-VTOL drones capable of carrying heavy loads, flying cars, delivery drones, urban mobility. The naming convention for this series  is HB+number+propeller size. The number is the combo continuous thrust of the rotor, it is easy for the customer to choose the combo he want .like HB30-54X24 is mean the continuous thrust is 30kgf, the propeller size is 54(inch)X 24(pitch). The FOC ESC had turned the firmware with the motors and propeller.