A probehead of an NMR-MAS apparatus includes a sample which has a rotation axis tilted by an angle θ>0 with respect to the z-axis. The angle θ can be adjusted about a target angle θtarget by tilting around a tilt axis. The rotation axis has a fixed angle with respect to the probehead, and the NMR-MAS apparatus tilts at least part of the probehead to adjust the angle θ. The probehead has an outer contour K between an upper end and a lower end. For all z between the upper end and the lower end, a cross-section S(z) of the contour K exists parallel to the xy-plane with a width Q(z) in the x-direction. The width Q(z) is smaller at points away from z=0, such that Q(z1) 0.