Initial value of the K_stab parameter normalised to the a₃/a ratio (y-axis), and of the ϵ_KL parameter normalised to 0.1 (x-axis) for models in SET4. The semiplane defined by K_stab < a₃/a − ϵ_KL < 0.1 contains triples in an initially stable configuration possibly prone to eccentric KL effects. Red squares mark the triples in which the inner BHB merges within 14 Gyr. The colour coding marks the ratio between the initial and final value of the merger time, t_GW, f/t_GW, i.