Distribution of rotational velocities of our final sample of 63 O-type isolated stars in Cygnus OB2. Left: histogram color-coded on the basis of the resolving power of the spectra used for each target. Middle: v sin i histogram showing the comparison between the distribution of rotational velocities found for our sample of O-type stars in Cygnus OB2 and the distribution of O-type stars found in the MW. Vertical black lines indicate the associated Poisson noise. Right: as in middle panel but compared to 30 Dor.