The EQF3300 can measure the activity concentrations of radon and thoron and their short-lived decay products. Sampling is performed using a filter in the device’s removable measuring head. Unlike the EQF3320, both the unadsorbed (free, atomic) and adsorbed fractions are collected. A Hall-effect detector is located directly above the filter to determine the activity collected on the filter. The measuring head is designed with a minimal surface area so that the collection losses of the unbound fraction are low. The measurement geometry is optimized for long filter service life and high sensitivity. The filter is easily accessible and can be replaced without tools. The measuring head is detachable from the device. The air sample enters the device’s radon measuring chamber via the connecting hose. The spectroscopic measurement method offers the shortest response and decay times and prevents progressive contamination of the measuring chamber by 210Po. Thanks to the special design of the four measurement chambers, sensitivity remains constant even at high humidity, eliminating the need for a desiccant cartridge. Environmental conditions, operating states, and relevant events are recorded by the device. A flexible alarm system allows the user to implement custom warning and alarm functions. Additional sensors can be connected to the accessory port on the front panel. The built-in GPS receiver provides the corresponding measurement location for map display in the dVISION operating software. The large, bright color display with intuitive touch menus offers modern ease of use and access to all relevant information. With its configurable digital and analog interfaces, the device can be integrated into any network. The EQF3300 is manufactured entirely at our facility in Dresden and calibrated in our DAkkS-accredited calibration laboratory. Only high-quality components are used in the device, and thanks to its design and choice of materials, the EQF3300 is nearly 100% recyclable.