Two millimeter diameter spherical rotors spinning at 68 kHz for MAS NMR

•Spinning frequency > 68 kHz of 2 mm spherical rotors using helium spinning gas.•Magic angle adjustment at spinning frequency of 59.3 kHz using KMnO4.•Nonregulated spinning stability of ±0.5% during data acquisition.•Improvements on stator and RF coil results in three-fold increase in NMR sensitivity.•Customized narrow-bore transmission line probe for 2 mm spheres.