Typical evolution of a binary that becomes an LMXB and ends up as a merging NS-NS in Model 1. The timescale (in Myr) is shown on the left side of the panel, the masses (in M_⊙) are marked next to the stars they refer to, and the orbital separation (a in R_⊙) and eccentricity (e) of the system at a given stage of the evolution are shown on the right side of the panel. The acronyms on the figure stand for: MS - main sequence star HG - Hertzsprung gap star RG - first giant branch star CHeB - core helium burning star HeMS - main sequence naked helium star HeHG - Hertzsprung gap naked helium star NS - neutron star BH - black hole CE - common envelope SN - supernova explosion nRLOF - nuclear Roche lobe overflow TTMT - thermal time-scale mass transfer