For frequently recurring tasks in quality assurance, water-equivalent RW3 material is an integral and time-efficient tool for every medical physicist. Our EASY CUBE phantom is made of RW3 and therefore perfectly suited for these requirements. By its modular design and various extensions, the EASY CUBE phantom can also be used for so-called End-to-End QA tests to verify the whole treatment chain. EASY CUBE supports QA measurements in dosimetry and beyond in the field of radiation oncology. The phantom can be used in combination with irradiation detectors like ionization chambers, radiosensitive films and TLDs. The detectors are positioned inside the phantom with appropriate adapters which consist of the same material as the phantom.