OTC 6111 T55 Torx 3/8" Square Drive Socket
This is one of many torx bit sockets from OTC, it's separate, however, they do come in a set.  This particular one is a T55 with a 3/8" drive.  It's made of S2 steel to meet or exceed torque specifications.  The two piece design, makes it stronger and allows for a longer tool life.  Also, it's backed by OTC's lifetime marathon warranty.