Different thresholds for thermal-timescale mass transfer applied to a 3.2 M_⊙ AGB star (R_i = 206 R_⊙). The black solid line is the radius response to thermal equilibrium mass loss, the red dashed line shows the inner radius R_KH as a function of its remnant mass, the blue dashed–dotted line gives the inner Roche-lobe radius ﹩{R}_{{{\rm{L}}}_{1}}﹩ with an initial mass ratio q_i = 1.557, the green dashed–dotted–dotted line shows the outer Roche-lobe radius ﹩{R}_{{{\rm{L}}}_{2}}﹩ with an initial mass ratio q_i = 1.427, and the gray dotted line is the inner Roche-lobe radius ﹩{R}_{{{\rm{L}}}_{1}}﹩ with an initial mass ratio q_i = 0.673.