STIS rest-frame spectra of eight z ∼ 0.3 − 0.4 LyC emitters. They are ordered by decreasing f_esc from top to bottom, except for J1248+4259, which is shown at the top with a dotted line (see text for details). The colored area shows the spectra of the three strong LyC leakers (f_esc >  0.1). The C IV λ1550, C III] λ1909, and He II λ1640 lines are clearly detected in the strongest LyC leakers (J1243+4646, J1154+2443, and J1152+3400, with escape fractions between f_esc = 0.13 and 0.72), which are characterized by a high C IV/C III] ratio. All the spectra show C III] λ1909 emission (with EWs of ∼5 − 20 Å rest frame) and other weaker lines.