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Stars which are rapidly rotating are expected to show high levels of activityaccording to the activity-rotation relation. However, previous TESS studieshave found Ultra Fast Rotating (UFR) M dwarfs with periods less than one daydisplaying low levels of flaring activity. As a result, in this study, weutilise VLT/FORS2 spectropolarimetric data of ten M dwarf UFR stars betweenspectral types $\sim$M2 - M6 all with $P_{\rm rot} <$ 1, to detect the presenceof a magnetic field. We divide our sample into rotation period bins of equalsize, with one star having many more flares in the TESS lightcurve than theother. We also provide an analysis of the long-term variability within oursample using TESS lightcurves taken during Cycles 1 and 3 (up to three yearsapart). We identify 605 flares from our sample which have energies between2.0$\times$10$^{31}$ and 5.4$\times$10$^{34}$ erg. Although we find nosignificance difference in the flare rate between the Cycles, two of ourtargets display changes in their lightcurve morphology, potentially caused by adifference in the spot distribution. Overall, we find five stars (50%) in oursample have a detectable magnetic field with strengths $\sim$1 - 2 kG. Of thesefive, four were the more flare active stars within the period bins with onebeing the less flare active star. It would appear the magnetic field strengthmay not be the answer to the lack of flaring activity and supersaturation ormagnetic field configuration may play a role. However, it is clear therelationship between rotation and activity is more complex than a steadydecrease over time.

The Puzzling Story of Flare Inactive Ultra Fast Rotating M dwarfs. I. Exploring their Magnetic Fields