A seal to seal a gap between a rotatable component (4, 18) and a non-rotatable component comprises: A fastening section adapted to be fixedly mounted in relation to the non-rotatable component, a sleeve-like section (3) adapted to be mounted around the rotatable component (4, 18), a resilient section (7) between the sleeve-like and fastening section comprising an arcuate portion (8), and in an unmounted condition, the sleeve-like section (3) has an inner diameter, DSEAL, with a predefined magnitude relative to an outer diameter of the rotating component, DSHAFT, such that 0.9≦DSEAL/DSHAFT≦1.1.