A portable, battery-powered component of an alternating electric field cancer treatment system designed to generate intermediate-frequency (100-300 kHz) alternating electric current to treat certain forms of recurrent or newly-diagnosed cancer; typically glioblastoma multiforme (GBM) [malignant brain tumour]. Also known as tumour treatment fields (TTFields) or (TTF), the treatment is usually intended to be used as a home-use supplement to primary therapies (e.g., surgery, radiotherapy, and/or chemotherapy). Designed to be carried by the patient it is powered by a rechargeable battery pack or via a mains power supply and is connected to a head-worn transducer array via a connection cable.