A portable Halbach magnet that can be opened and closed without force: The NMR-CUFF

► Halbach magnets can be split and opened with minimal force. ► First prototype: 3.1 kg, flux density of 0.57 T, 3 cm inner diameter, opening force 20N. ► Can be mounted around slender objects that are part of larger or immobile whole. ► As a demonstration plants were imaged, sap flow measured and tree growth monitored. ► Ideal for portable NMR and sensor-like applications.