For use with External Torx head type bolts.

SOCKET E-SIZE INCH METRIC
E- 4 .15" 3.8MM
E- 5 .18" 4.7MM
E- 6 .22" 5.6MM
E- 7 .24" 6.1MM
E- 8 .29" 7.4MM
E-10 .36" 9.3MM
E-12 .43" 11.1MM
E-14 .50" 12.8MM
E-16 .57" 14.7MM
E-18 .65" 16.6MM
E-20 .72" 18.4MM
E-24 .87" 22.1MM