Activity-rotation diagram for Kepler single dwarfs with temperatures within 5200 and 5400 K, corresponding to the interval in which the stars belonging to NGC 6811 seem to cross the intermediate-P_rot gap. The black dots correspond to the individual stars, and the colored regions indicate the density of stars, as computed by the kernel density estimation. The blue arrow marks the local minimum in the S​_ph − P_rot relation associated with the intermediate-P_rot gap.